Evidence synthesis – Sleep duration and eating behaviours among adolescents: a scoping review

Abstract

Introduction: In the past decade, investigations of the relationship between sleep duration and eating behaviours have been emerging; however, a formal synthesis of the literature focussed on adolescent populations has not yet been conducted. We conducted a scoping review of the literature examining the relationship between sleep duration and eating behaviours in adolescents. Gaps in the research and directions for future research were identified based on the findings.

Methods: A systematic search was employed on four research databases: PubMed, PsycInfo, CINAHL and Scopus; relevant grey literature was also reviewed. Studies that reported on the relationship between sleep duration and eating behaviours among high school–aged adolescents were included in the review. Data were extracted, charted and synthesized into a narrative. Consistent with the purpose of a scoping review, the methodological quality of the studies was not appraised. Stakeholders were consulted to validate the findings and provide insight into the interpretation and identification of pressing gaps in the research that remain to be addressed.

Results: In total, 61 studies published between 2006 and 2021 met the criteria for review. Existing research focussed heavily on examining sleep duration in relation to intake of food from certain food groups, beverages and processed foods, and relied on a population study design, cross-sectional analyses and self-report measures.

Conclusion: Future research is needed to understand the link between sleep duration and eating-related cognition, eating contexts and disordered eating behaviours in order to better understand how ensuring sufficient sleep among adolescents can be leveraged to support healthier eating practices and reduce diet-related risks.

Keywords: sleep, dietary patterns, eating habits, youth, adolescents

Introduction

Evidence suggests that poor dietary patterns characterized by excessive intake of sugar, saturated fat and salt, as well as low intake of vegetables and whole grains, are associated with the development of noncommunicable diseases (e.g. diabetes).^{Footnote 1Footnote 2} The role of psychosocial eating habits, such as eating with other people and mindful eating, is also being increasingly recognized for its role in supporting healthy eating.^{Footnote 3Footnote 4} Hence, supporting healthy food consumption and eating habits is critical to prevent and manage diet-related diseases. Given the role of sleep in regulating hormones that affect appetite (e.g. insulin, leptin, ghrelin),^{Footnote 5Footnote 6Footnote 7Footnote 8} fostering adequate sleep among adolescents could support the development of a range of healthy behaviours during adolescence.^{Footnote 9Footnote 10Footnote 11}

Considering the importance of the adolescent period in the development of life-long behaviours, promoting healthy eating behaviours among adolescents is critical.^{Footnote 12} Adolescence is especially important because it is characterized by many developmental and behavioural changes, including a decline in healthy eating habits.^{Footnote 13} Additionally, changes to the circadian rhythm that occur during this developmental period result in a natural shift towards later sleep onset among adolescents.^{Footnote 14} This shift in the circadian rhythm can contribute to insufficient sleep, which is further compromised by changes such as early school start times, increased academic demands and extracurricular activities.^{Footnote 15Footnote 16Footnote 17} Therefore, examining the relationship between these two modifiable lifestyle factors (sleep duration and eating behaviours) among adolescents is necessary to better understand approaches to facilitating health and the development of healthy life-long behaviours.

Sleep is an essential component of healthy development during adolescence. For optimal health and well-being, it is recommended that adolescents aged 15 to 17 years get 8 to 10 hours of sleep per night.^{Footnote 18} In the past decade, adequate sleep as a lifestyle factor has garnered increasing attention in the literature. Short sleep duration over a prolonged period of time is associated with a range of adverse physical and emotional health outcomes (e.g. mood dysregulation, accidental injuries).^{Footnote 15Footnote 19} Insufficient sleep, in particular, has been associated with poor dietary intake and the development of diet-related diseases;^{Footnote 13Footnote 20} potentially in part due to alterations in metabolic hormone regulation, as well as extended waking hours.^{Footnote 5Footnote 11Footnote 21} Despite these potential links, little is known about the generalizability of the relationship between eating behaviours and sleep duration in adolescent populations. Thus, understanding this relationship is crucial for clinicians and researchers to better understand the complex relationships among sleep duration and diet-related diseases.^{Footnote 22}

The objectives of this scoping review were to systematically review the literature that examines sleep duration in relation to eating behaviours among adolescents, and to identify gaps and provide direction for future research in the field of adolescent health promotion.

Methods

This review follows the six-staged framework for scoping studies described by Arksey and O'Malley^{Footnote 23} and recommendations outlined by Levac and colleagues^{Footnote 24} to enhance the scoping review methodologies. The six stages of this framework are: (1) identifying the research question; (2) identifying relevant studies; (3) study selection; (4) charting the data; (5) collating, summarizing and reporting the results; and (6) consultation exercise.^{Footnote 23} The protocol for this study is available in further detail elsewhere.^{Footnote 25} This review is reported in accordance with the PRISMA Extension for Scoping Review (PRISMA-ScR) guidelines.^{Footnote 26Footnote 27}

Identifying the research questions

The primary research question guiding this scoping review was: what is the nature of the research on the relationship between sleep duration and eating behaviours in adolescents? Grounded in the objectives of performing a scoping review—to map the key concepts and evidence available on a research topic—the secondary research questions were: (1) which research designs have been employed?; (2) which adolescent populations have been studied?; (3) which outcome variables have been assessed?; and (4) what questions remain to be addressed? Methodological quality of the studies was not assessed, given the primary purpose of conducting a scoping review.^{Footnote 23}

Identifying relevant studies

To identify relevant studies, systematic searches were conducted on PubMed, CINAHL, PsycInfo, and Scopus. The most recent search strategy (Table 1) was executed on 17 November 2021. Grey literature studies were also reviewed using the template provided by Godin et al.^{Footnote 28} Using this guideline, a targeted search of relevant health organization websites and public health databases was conducted. The grey literature search was conducted on 20 March 2020.

Table 1. Keywords and search terms employed in the systematic search

Study population	Sleep duration	Eating behaviour
Youth	Sleep duration	Food
Adolescent	Sleep quantity	Diet
Adolescence	Sleep deprivation	Dietary
Teenager	Insufficient sleep	Dieting
Teen	Sleep restriction	Nutrition
	Deprived sleep	Weight control
	Restricted sleep	Eating behaviour
	Disrupted sleep	Eating
	Sleep disruption	Feeding behaviour
	Excessive sleep	Feeding
	Over sleep	Calorie
	Sleep disorders	Vegetables
	Insomnia	Fruit
	Hypersomnia	Soda
		Carbohydrates
		Fats
		Milk
		Proteins
		Snacks
		Sugar
		Obesity
		Binge
		Bingeing
		Anorexia
		Bulimia

Selecting the studies

The studies were screened to ensure that findings reported on the association between sleep duration and eating behaviours among adolescents (approximately 13–19 years of age). No restrictions were placed on research approaches, study design or study type. Studies that solely examined infants, toddlers, preschoolers, school-aged children, adults or older adults were excluded. Only studies reported in English and in the form of a publication, thesis, dissertation, technical report or conference proceedings were included in the final review.

Studies were screened using a two-level screening process to determine eligibility. Studies were first reviewed based on the title and abstract, and then selected for inclusion in the final review based on reading the article in full. In the first stage, the title and abstract of each study were independently screened by one reviewer to determine potential eligible studies. In the second stage, the full text of each study was screened by two reviewers, after which the reviewers met to discuss the cases for which the decision was not unanimous, in order to reach consensus.

Charting the data

The data extraction stage followed the two-step recommendations by Daudt et al.^{Footnote 29} To ensure the validity of the data extracted, the review team met to discuss the data extraction protocol. Following that, each member of the review team independently extracted data from articles that were purposely chosen to represent a range of themes and study designs. After independently extracting data from the same set of studies, the review team reconvened to discuss discrepancies before independently extracting data from the remaining studies. Key characteristics were extracted and recorded using a spreadsheet, including publication, study and population characteristics. Data pertaining to the research focus on sleep duration and eating behaviours were extracted. The first author reviewed the data extracted from all studies for accuracy.

Collating, analyzing and synthesizing the data

The charted data were collated, analyzed and synthesized to summarize the current body of literature on sleep duration and eating behaviours in adolescent populations. This summary is presented in the form of aggregate numeric values and narrative descriptions in the results section. The findings are grouped under two primary domains: food consumption and eating habits.

Consulting stakeholders

Based on the grey literature review, three stakeholders were identified, and two were contacted via email. These two stakeholders were specifically consulted based on their content expertise (e.g. adolescent health, eating- and weight-related behaviours) and profession. One was a researcher and clinician, and the other was a clinician and community worker. Both stakeholders agreed to participate in a consultation for this scoping review. The first stakeholder was a youth health researcher, with frontline clinical experiences, specializing in population-level primary prevention and health promotion research. The second stakeholder was an education and outreach coordinator and psychotherapist, for a national organization that delivers community education and school-based prevention programming. During the consultations, the first author shared preliminary findings and validated the interpretations with the stakeholders. Stakeholders were solicited for their perspectives on important directions for future research in the field and provided relevant articles for the team to review. The perspectives gathered through the consultation exercise guided the reporting and interpretation of the results. The areas identified as priorities for future research were used to frame the discussion of the results.

Results

Study selection

The systematic and grey literature searches yielded 2185 and 106 citations, respectively. After removing duplicates, the remaining 2291 citations were screened. A total of 61 articles from the systematic and grey literature searches met eligibility criteria and were included in the final synthesis (Figure 1).

Figure 1 - Text description

This figure illustrates the PRISMA flow chart for the identification, screening, eligibility and inclusion of studies in the evidence synthesis.

Records were identified through database searching (n = 2185), and additional records were identified through other sources (n = 106). After duplicates were removed, n = 2291 records remained. Those 2291 records were screened, which led to the exclusion of n = 2033 records. The remaining n = 258 full-text articles were assessed for eligibility, of which n = 197 full-text articles were excluded. This resulted in n = 0 studies being included in the qualitative synthesis, and n = 61 studies being included in the quantitative synthesis (scoping review).

Publication, study and population characteristics

Tables 2 and 3 present the study characteristics of the peer-reviewed and grey literature studies included in the final review, respectively. All studies were published between 2006 and 2021. Most of the studies were conducted in North America (36.1%), Europe (23.0%) and East Asia (13.1%). The sample size of the included studies ranged from 21 to 1 777 091, with a median sample size of 1522.

Table 2. Publication characteristics of the studies included from the systematic search

No.	Title	Authors	Year	Country
1	The influence of adherence to the Mediterranean diet on academic performance is mediated by sleep quality in adolescents	Adelantado-Renau et al.Footnote 68	2019	Spain
2	Subjective sleep duration and quality influence diet composition and circulating adipocytokines and ghrelin levels in teen-age girls	Al-Disi et al.Footnote 61	2010	Saudi Arabia
3	Relative contribution of obesity, sedentary behaviors, and dietary habits to sleep duration among Kuwaiti adolescents	Al-Haifi et al.Footnote 42	2016	Kuwait
4	Lifestyle correlates of self-reported sleep duration among Saudi adolescents: a multicentre school-based cross-sectional study	Al‐Hazzaa et al.Footnote 43	2014	Saudi Arabia
5	The association between obstructive sleep apnea and dietary choices among obese individuals during middle to late childhood	Beebe et al.Footnote 62	2011	United States
6	Psychiatric morbidity and dietary habits during COVID-19 pandemic: a cross-sectional study among Egyptian youth (14–24 years)	Alamrawy et al.Footnote 59	2021	Egypt
7	Association of overweight, obesity and insufficient sleep duration and related lifestyle factors among school children and adolescents	Almulla and ZoubeidiFootnote 49	2021	United Arab Emirates
8	Association between food patterns and difficulties in falling asleep among adolescents in Norway — a descriptive Young-Hunt3 study	André et al.Footnote 46	2021	Norway
9	Association between self-reported sleep duration and dietary quality in European adolescents	Bel et al.Footnote 67	2013	Germany, Belgium, Italy, France, Spain, Austria, Greece, Sweden, United Kingdom
10	Short sleep duration is associated with specific food intake increase among school-aged children in China: a national cross-sectional study	Cao et al.Footnote 31	2019	China
11	How do energy balance-related behaviors cluster in adolescents?	Collese et al.Footnote 90	2018	Maringa (Brazil), Athens (Greece), Dortmund (Germany), Ghent (Belgium), Heraklion (Greece), Lille (France), Pecs (Hungary), Rome (Italy), Stockholm (Sweden), Vienna (Austria) and Zaragoza (Spain)
12	The impact of short sleep on food reward processes in adolescents	Duraccio et al.Footnote 91	2019	United States
13	Effects of sleep restriction on food-related inhibitory control and reward in adolescents	Duraccio et al.Footnote 76	2019	United States
14	Sleep and pre-bedtime activities in New Zealand adolescents: differences by ethnicity	Galland et al.Footnote 58	2020	New Zealand
15	Short sleep duration is associated with increased obesity markers in European adolescents: effect of physical activity and dietary habits. The HELENA study	Garaulet et al.Footnote 33	2011	Austria, Belgium, France, Germany, Greece, Hungary, Italy, Spain, Sweden
16	A chrononutrition perspective of diet quality and eating behaviors of Brazilian adolescents in associated with sleep duration	Garcez et al.Footnote 72	2021	Brazil
17	Sleep duration or bedtime? Exploring the association between sleep timing behaviour, diet and BMI in children and adolescents	Golley et al.Footnote 52	2013	Australia
18	Family dinner frequency is inversely related to mental disorders and obesity in adolescents: the CASPIAN-III study	Haghighatdoost et al.Footnote 73	2017	Iran
19	Sleep patterns and quality are associated with severity of obesity and weight-related behaviors in adolescents with overweight and obesity	Hayes et al.Footnote 55	2018	United States
20	Racial/ethnic disparity in habitual sleep is modified by caloric intake in adolescents	He et al.Footnote 64	2020	United States
21	Habitual sleep variability, not sleep duration, is associated with caloric intake in adolescents	He et al.Footnote 56	2015	United States
22	Behaviors associated to sleep among high school students: cross-sectional and prospective analysis	Hoefelmann et al.Footnote 74	2014	Brazil
23	Association between unhealthy behavior and sleep quality and duration in adolescents	Hoefelmann et al.Footnote 92	2015	Brazil
24	Dietary intake and eating-related cognitions related to sleep among adolescents who are overweight or obese	Ievers-Landis et al.Footnote 63	2016	United States
25	Dietary patterns in relation to prospective sleep duration and timing among Mexico City adolescents	Jansen et al.Footnote 45	2020	Mexico
26	Relationships of beverage consumption and actigraphy-assessed sleep parameters among urban-dwelling youth from Mexico	Jansen et al.Footnote 66	2021	Mexico
27	Insomnia among Japanese adolescents: a nationwide representative survey	Kaneita et al.Footnote 75	2006	Japan
28	Associations of sleep duration and quality with disinhibited eating behaviors in adolescent girls at-risk for type 2 diabetes	Kelly et al.Footnote 53	2016	United States
29	Cross-sectional study of randomly selected 18-year-old students showed that body mass index was only associated with sleep duration in girls	Kjartansdóttir et al.Footnote 93	2018	Iceland
30	Sleep restriction is not associated with a positive energy balance in adolescent boys	Klingenberg et al.Footnote 54	2012	Denmark
31	Do sleep-deprived adolescents make less-healthy food choices?	Kruger et al.Footnote 34	2014	United States
32	Sleep duration's association with diet, physical activity, mental status, and weight among Korean high school students	LeeFootnote 51	2017	South Korea
33	Associations of weekday and weekend sleep with children's reported eating in the absence of hunger	LeMay-Russel et al.Footnote 78	2019	United States
34	Interactions between energy drink consumption and sleep problems: associations with alcohol use among young adolescents	MarmorsteinFootnote 57	2017	United States
35	Neural mechanisms that promote food consumption following sleep loss and social stress: an fMRI study in adolescent girls with overweight/obesity	Jensen et al.Footnote 101	2021	United States
36	Associations of sleep duration and social jetlag with cardiometabolic risk factors in the study of Latino youth	Johnson et al.Footnote 69	2020	United States
37	Factors associated with sleep duration among pupils	Kohyama et al.Footnote 94	2020	Japan
38	Association between self-reported sleep duration and dietary nutrients in Korean adolescents: a population-based study	Lee et al.Footnote 65	2020	Korea
39	Sleep-related problems and eating habits during COVID-19 lockdown in a southern Brazilian youth sample	López-Gil et al.Footnote 37	2021	Brazil
40	Relationships between hours of sleep and health-risk behaviors in US adolescent students	McKnight-Eily et al.Footnote 48	2011	United States
41	The association between sleep duration, sleep quality, and food consumption in adolescents: a cross-sectional study using the Korea Youth Risk Behavior Web-based Survey	Min et al.Footnote 44	2018	Korea
42	Energy drink consumption among Australian adolescents associated with a cluster of unhealthy dietary behaviours and short sleep duration	Nuss et al.Footnote 95	2021	Australia
43	Clustering of energy balance-related behaviours, sleep, and overweight among Finnish adolescents	Nuutinen et al.Footnote 96	2017	Finland
44	Association between unhealthy dietary behaviors and sleep disturbances among Japanese adolescents: a nationwide representative survey	Otsuka et al.Footnote 79	2019	Japan
45	Associations of sleep with food cravings and loss-of-control eating in youth: an ecological momentary assessment study	Parker et al.Footnote 77	2021	United States
46	Clustering of dietary patterns, lifestyles, and overweight among Spanish children and adolescents in the ANIBES study	Perez-Rodrigo et al.Footnote 97	2015	Spain
47	Sleep duration and consumption of sugar-sweetened beverages and energy drinks among adolescents	Sampasa-Kanyinga et al.Footnote 47	2018	Canada
48	Association between short time in bed, health-risk behaviors and poor academic achievement among Norwegian adolescents	Stea et al.Footnote 50	2014	Norway
49	Breakfast skipping in Greek schoolchildren connected to an unhealthy lifestyle profile. Results from the National Action for Children's Health program	Tambalis et al.Footnote 71	2019	Greece
50	Insufficient sleep duration is associated with dietary habits, screen time, and obesity in children	Tambalis et al.Footnote 98	2018	Greece
51	Sleep duration and behavioral correlates in middle and high school students: a cross-sectional study in Zhejiang province, China	Wang et al.Footnote 38	2021	China
52	The association of sleep duration with adolescents' fat and carbohydrate consumption	Weiss et al.Footnote 99	2010	United States
53	Self-reported sleep duration and weight-control strategies among US high school students	Wheaton et al.Footnote 80	2013	United States
54	Sleep duration and weight-related behaviors among adolescents	Widome et al.Footnote 36	2019	United States

Table 3. Publication characteristics of the studies included from the grey literature review

No.	Title	Author	Year	Country
1	#consumingitall: Understanding the complex relationship between media consumption and eating behaviors	AlbertFootnote 41	2017	United States
2	Are eating habits associated with adequate sleep among high school students?	Bhurosy and ThiagarajahFootnote 30	2020	United States
3	Obesity and sleep: assessing risk among African American adolescent girls in Chicago	BrakefieldFootnote 100	2012	United States
4	European adolescents' level of perceived stress is inversely related to their diet quality: the Healthy Lifestyle in Europe by Nutrition in Adolescence study	De Vriendt et al.Footnote 70	2012	Belgium
5	Sleep quality and duration is related with diet and obesity in young adolescent living in Sicily, Southern Italy	Ferranti et al.Footnote 32	2016	Italy
6	Characteristics associated with sleep duration, chronotype, and social jet lag in adolescents	Malone et al.Footnote 40	2016	United States
7	Association of sleep duration and snack consumption in children and adolescents: the CASPIAN‐V study	Mozaffarian et al.Footnote 35	2020	Iran

Table 4 presents the study and population characteristics of the 61 included studies. Most studies published on this topic used a cross-sectional design (86.9%), were observational in nature (93.4%) and took place in a school setting (57.4%). Many studies exclusively examined adolescents within the high school age range (41.0%); however, some also included younger (50.8%) or older (3.3%) adolescents in their sample. With the exception of four (and three that did not specify), most studies examined both males and females (88.5%).

Table 4. Study characteristics of included studies

Characteristic		Frequency	%
Year	2006–2010	2	0.03
	2011–2015	15	24.6
	2016–2020	39	63.9
	2021–2025	5	8.2
Region	Asia	8	13.1
	Europe	14	23.0
	Middle East	7	11.5
	North America	22	36.1
	Oceania	3	4.9
	South America	7	11.5
Publication type	Dissertation	2	3.3
	Original research	59	96.7
Study design	Cross-over	2	3.3
	Cross-sectional	53	86.9
	Prospective	5	8.2
	Randomized control	1	1.6
Study type	Experimental	3	4.9
	Intervention	1	1.6
	Observational	57	93.4
Setting	School	35	57.4
	Clinic	12	19.7
	CombinationFootnote a	1	1.6
	Community	12	19.7
	Laboratory	1	1.6
Age group	High school–aged and younger	31	50.8
	High school–aged and older	2	3.3
	High school–aged only	25	41.0
	Not specified	3	4.9
Sex/gender	Female only	3	4.9
	Male only	1	1.6
	Both	54	88.5
	Not specified	3	4.9

The published research in this domain predominantly used self-report measures of sleep duration; 72.1% of the studies included in our review used such self-report measures (e.g. questionnaire, sleep diary, interview recall, guardian report). Objective measures of sleep duration were used in 16.4% of studies (e.g. actigraphy, accelerometer, polysomnography) and a combination of self-report and objective measures of sleep duration were used in 9.8% of the studies (data not shown).

Most studies examined multiple aspects of eating behaviours using self-report measures. In 72.1% of studies, self-report questionnaires were used and in 14.8% of studies, interview methods were used to obtain a measure of dietary intake. In 6.6% of studies, objective measures of dietary intake, such as analysis of meal orders and absolute caloric intake, were used. Two studies assessed eating behaviours using experimental tasks (3.3%). One study used food records (1.6%), and another used a combination of 24-hour recall and food records (1.6%).

Research focus on sleep duration and eating behaviour studies

Table 5 presents the frequency with which the research foci were reported in the literature.

Table 5. Research focus of sleep duration and eating behaviour research

Variable or measure	n
Eating behaviour variable
Food group intake (e.g. vegetables, fruit, meat, milk)	25
Beverage intake (e.g. sugar-containing beverages)	22
Meal consumption patterns (e.g. skipping breakfast)	18
Processed food intake (e.g. chocolate, candy, fried potatoes)	15
Energy intake (e.g. total calories)	11
Caffeinated beverage intake (e.g. coffee, energy drinks)	9
Eating-related cognition (e.g. dietary restraint)	7
Macronutrient intake (e.g. protein, fat, carbohydrate)	7
Dietary quality	6
Eating context (e.g. location, people)	5
Disordered eating (e.g. bingeing)	4
Eating behaviour measure
Self-reported questionnaire	44
Interview recall	9
Objective measure	4
Experimental task	2
Combination	1
Food record	1

Food consumption

Food group intake

Indicators of food groups were represented in the largest number of studies. The food group most commonly assessed was fruit and vegetables. Among studies that examined fruit and vegetable intake, findings were mixed. Ten studies found that vegetable consumption was positively associated with sufficient sleep.^{Footnote 30Footnote 31Footnote 32Footnote 33Footnote 34Footnote 35Footnote 36Footnote 37Footnote 38Footnote 39} One study found that higher intake of fruit and vegetables was associated with shorter self-reported sleep duration.^{Footnote 40} One study found that longer sleep duration was associated with higher fruit and vegetable consumption in males, but not females.^{Footnote 41} Two studies did not reveal any significant associations between fruit and vegetable consumption and sleep duration.^{Footnote 42Footnote 43} Eight studies reported on intake of milk and dairy products, meat and alternatives and grain products, and the findings were mixed.^{Footnote 30Footnote 31Footnote 33Footnote 35Footnote 42Footnote 44Footnote 45Footnote 46}

Beverage intake

Beverage intake was the second most frequently examined variable. A number of studies observed that short sleep was associated with greater intake of sugar-sweetened beverages^{Footnote 31Footnote 35Footnote 36Footnote 42Footnote 47} and soft drinks.^{Footnote 44Footnote 48Footnote 49} One study observed that short sleep was associated with lower odds of intake of soft drinks without sugars.^{Footnote 35}

Processed food intake

Studies frequently reported on intake of processed foods, including fast food, sweets and salty snacks. Among these studies, it was often reported that short sleep was associated with higher consumption of fast food,^{Footnote 34Footnote 42} sweets^{Footnote 32Footnote 42Footnote 44Footnote 50} and salty snacks,^{Footnote 32Footnote 35Footnote 51} with the exception of one study that did not find a significant association between sleep duration and fast food consumption.^{Footnote 38}

Energy intake

Energy intake, or caloric intake, was a common indicator examined among the studies. Studies reported mixed findings regarding the direction and significance of the relationship between sleep duration and energy intake. Some studies reported findings that suggest that short sleep duration was associated with higher energy intake,^{Footnote 52Footnote 53} while one study reported short sleep duration was associated with a small negative energy balance,^{Footnote 54} and two reported insignificant findings.^{Footnote 55Footnote 56}

Caffeinated beverage intake

Nine studies examined the associations between sleep duration and caffeinated beverages.^{Footnote 35Footnote 36Footnote 42Footnote 47Footnote 49Footnote 51Footnote 57Footnote 58Footnote 59} Of these, four reported significant findings that consumption of caffeinated beverages was associated with shorter sleep duration.^{Footnote 47Footnote 49Footnote 57Footnote 58} One study found that short sleep was associated with a decreased intake of coffee.^{Footnote 35}

Macronutrient intake

Intake of macronutrients was reported in eight studies.^{Footnote 56Footnote 60Footnote 61Footnote 62Footnote 63Footnote 64Footnote 65Footnote 66} Using 24-hour-food-recall questionnaires and wrist-actigraphy measures, one study found that those who slept less than eight hours consumed a higher proportion of calories from fat and a lower proportion of calories from carbohydrates, compared to adolescents sleeping eight hours or more.^{Footnote 60} Another study observed that girls who slept less than five hours a night ate a higher proportion of carbohydrates.^{Footnote 61}

Dietary quality

Six studies assessed dietary quality.^{Footnote 67Footnote 68Footnote 69Footnote 70Footnote 71Footnote 72} The findings related to dietary quality were mixed, with two studies reporting that insufficient sleep was associated with poorer dietary quality^{Footnote 67Footnote 72} and another two studies reporting no significant relationship between sleep duration and dietary quality.^{Footnote 68Footnote 69} Furthermore, one study reported a significant association between sleep duration and dietary quality in the context of the association between perceived stress and dietary quality.^{Footnote 70}

Eating habits

Meal consumption patterns

Among the studies that examined eating habits, meal consumption pattern was the most commonly examined in relation to sleep duration. Breakfast consumption was examined in all studies except one.^{Footnote 59} Lunch, dinner and snack consumption was examined in a very few studies.^{Footnote 73Footnote 74} Among the studies examining eating habits, it was commonly found that skipping a meal, especially breakfast, was associated with less optimal sleep duration.^{Footnote 30Footnote 36Footnote 37Footnote 38Footnote 42Footnote 43Footnote 50Footnote 71} Two studies found that the prevalence of sleep disorders, such as insomnia, were higher for meal skippers.^{Footnote 69Footnote 75}

Eating-related cognitions

Cognitive factors associated with eating emerged as a theme in the literature. Using an experimental study design, one study found that following sleep restriction, adolescents performed more poorly on food-related inhibitory control,^{Footnote 76} and another found that short sleep duration was associated with loss-of-control eating.^{Footnote 77} Additionally, an interaction was identified whereby adolescents with a BMI in the normal weight range had a heightened response to food reward following sleep restriction. One study found that average weekday sleep duration was negatively associated with eating in the absence of hunger, and the reverse was observed for average weekend sleep duration.^{Footnote 78}

Eating contexts

Contextual factors surrounding eating were identified as a theme in the variables investigated. One study measured a number of weight-related behaviours, including eating habits such as eating when full.^{Footnote 36} Another study found that sleep duration provided a partial explanation for the relationship between media consumption (e.g. listening to music, watching television, playing video games, instant messaging, emailing) and eating behaviours, but only for specific media and only in males.^{Footnote 41} One study found that longer sleep duration was associated with fewer times eating outside of the home in a week.^{Footnote 32} The findings from a study conducted in Japan indicated that short sleep duration was associated with family meal frequency.^{Footnote 79}

Disordered eating

Two studies found that very short sleep duration was significantly associated with weight control strategies, such as fasting and purging and eating fewer calories, among adolescent boys and girls.^{Footnote 38Footnote 80} Another study examined the associations among sleep duration, daytime sleepiness and disinhibited eating, including binge eating.^{Footnote 53} One study observed that emotional and night eating emerged during the COVID-19 pandemic, and was associated with symptoms of insomnia.^{Footnote 59}

Discussion

Summary of evidence

The objective of this scoping review was to explore and synthesize the literature on sleep duration and eating behaviours in adolescents. In total, 61 articles were included in this synthesis. This review also mapped out the characteristics of existing research by examining the research designs, study populations, outcome variables and research gaps in the current body of literature. To our knowledge, this is the first synthesis published on the topic.

The majority of studies were observational, employed a cross-sectional design, used a school-based population and were published in North America. With respect to methodologies used when assessing eating behaviours, the review identified that the current research focussed heavily on the intake of food and beverages through self-reported questionnaires. This synthesis also revealed a heavy emphasis on eating behaviours related to food group intakes, such as fruit and vegetables. Intakes of beverages and processed food were also very commonly investigated variables. Surprisingly, few studies examined eating habits in relation to sleep duration. Among the studies that examined eating habits, the majority focussed on breakfast consumption, with very few studies including measures of eating-related cognitions, eating contexts or disordered eating.

A prominent gap in the literature is the limited examination of eating habits as opposed to food consumption. Only four studies examined the contextual factors that surround eating, including eating in the absence of hunger, eating with family and friends and eating while consuming media, in relation to sleep duration in adolescents. This gap is critical to address because of the influence of sleep on eating behaviours, and the increasing recognition of the role of eating habits in overall healthy eating practices.^{Footnote 3Footnote 81} Therefore, further investigation into the connections between sleep duration and eating habits of adolescents is warranted.

An area that remains to be addressed is how sleep duration is implicated in disordered eating behaviours among adolescents. Previous research has identified that disordered eating and eating disorders often emerge during adolescence and early adulthood.^{Footnote 82} However, there is limited research examining the association between sleep duration and disordered eating among adolescents. Of particular relevance to this review is the role of insufficient sleep on binge eating. Research demonstrates that inadequate sleep is associated with binge eating, partly due to decreasing leptin (reduces appetite) and increasing ghrelin (stimulates appetite).^{Footnote 83} However, chronic energy restriction has also been demonstrated to compromise sleep health through mechanisms such as reducing orexin, which plays a role in regulating arousal, hunger and wakefulness,^{Footnote 84} and compromising sleep by increasing wake time and shallow sleep.^{Footnote 85} Considering the bidirectional nature of the relationship between sleep and disordered eating, this area of research requires further investigation.

Additionally, two factors that impact sleep duration and eating behaviours that were not adequately addressed are the role of stress, and changes in metabolic hormones. Research demonstrates that stressful life events impact sleep through alterations to the duration and quality of sleep; however, very few studies reviewed in this synthesis examined the influence of stress on the eating behaviours of adolescents. Research also demonstrates that those experiencing shorter sleep and  stress exhibit changes in metabolic hormones (e.g. reduced leptin and elevated ghrelin), which likely contributes to an increase in appetite and changes in eating behaviours^{Footnote 8Footnote 86} and altered inhibitory control.^{Footnote 76} Therefore, addressing this gap in the literature is crucial to better understanding the potential moderating effects of stress on sleep and eating-related cognitions, such as eating in the absence of hunger and disinhibited eating.

The overwhelming majority of studies published on this topic used a cross-sectional approach and were observational in nature. Self-report measures were used the majority of the time as indicators of sleep duration and eating behaviours. To develop a clearer understanding of the nature of the relationship between sleep duration and eating behaviours in adolescents, a wider variety of research designs and methods should be employed. The predominantly cross-sectional nature of the study designs and analyses does not enable inferences into the temporality of the associations observed. Future studies using a prospective cohort design are required to assess the temporality and bidirectional nature of the associations between sleep duration and eating behaviours.

Strengths and limitations

One of the strengths of this review is that we included the optional step of engaging stakeholders.^{Footnote 23} By engaging stakeholders, we were able to share and validate preliminary findings and solicit the perspectives of researchers and clinicians working in the community. Additionally, reliability checks were conducted throughout the scoping review, incorporating steps such as having two or more members of the research team review articles during the data selection and extraction stages.

There are limitations to this review. Unlike other kinds of reviews (e.g. systematic, meta-analytical), scoping reviews are not designed to evaluate the strength of associations between the variables or the quality of studies that were reviewed.^{Footnote 87Footnote 88} Thus, neither the strength of the associations observed nor the quality of the included studies in our review were assessed. Instead, scoping reviews are used to gather information from a range of study designs and methods in order to identify the types of evidence available in a given field and to identify knowledge gaps; they can serve as a precursor to a systematic review.^{Footnote 89}

Another limitation to this review is that only studies published in English were screened.

Finally, there is a possibility that relevant articles were inadvertently excluded. Although the search strategy was designed in consultation with subject specialist librarians, less commonly used terms in the literature may have been overlooked in the final search strategy.

Conclusion

Although research on sleep duration and eating behaviours in adolescent populations has been increasingly published in the past decade, much remains to be examined in this field. Further research on this topic is necessary in order to better understand how ensuring sufficient sleep among adolescents can support healthier eating practices. Future research should investigate how insufficient sleep may impact the eating habits of adolescents, including eating-related cognition, eating contexts and disordered eating behaviours. These lines of inquiry could contribute to supporting healthy eating among adolescents and informing behavioural interventions aimed at managing diet-related conditions.

Acknowledgements

 The authors would like to thank the liaison librarians at the University of Waterloo for their guidance in developing the literature search strategy and review protocol.

Conflicts of interest

 None.

Funding

 This research did not receive any specific grants from funding agencies in the public, commercial or not-for-profit sectors.

Authors' contributions and statement

 All authors contributed meaningfully to the preparation, drafting and editing of this paper. ND designed the protocol and led all aspects of the study, including data collection, extraction, charting, synthesis, stakeholder consultations and writing. AP, KR and EVB engaged in data collection and extraction. KR wrote the introduction, ND wrote the methods and results and AP wrote the discussion. EVB critically reviewed all components of the manuscript. MAF supervised the research, revised the manuscript and approved the final manuscript.

The content and views expressed in this article are those of the authors and do not necessarily reflect those of the Government of Canada.

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