Introduction
Headache and sleep complaints are prevalent in the general population and often coexist in the same subject [
1]. Excessive daytime sleepiness (EDS) is associated with neurological disorders and pain [
2,
3]. Only a few studies have investigated EDS in headache [
4‐
10], and the results are not uniform, possibly due to differences in methods and patient populations [
4‐
10]. We have previously reported on the prevalence of EDS in primary chronic headaches in the general population [
11].
To our knowledge EDS has not been evaluated in people with secondary chronic headache. Thus, in the present study we investigated the prevalence of, and factors associated with EDS in participants from the general population with different secondary chronic headaches.
Results
In total 93 of the 113 eligible participants (82%) completed the ESS. Respondents and non-respondents to the ESS did not differ in age, gender composition or the distribution of headache diagnoses (data not shown).
A total of 36 people had CPTH, 19 people had CEH and 40 people had HACRS. Co-occurrence of CPTH and CEH was found in 7 people, while one person had co-occurrence of CPTH and HACRS. Six persons had other secondary chronic headaches, i.e. 3 post-craniotomy, 1 diving related, 1 pregnancy-related, and 1 post-meningitis.
Seven of those with CPTH, seven of those with CEH and ten of those with HACRS reported EDS, respectively. Only one of those with other secondary chronic headache reported EDS.
The people with CPTH and CEH were descriptive similar (gender, co-occurrence of migraine, medication overuse, ESS or EDS) and were merged for the purpose of statistical analyses. We included people with CPTH/CER and HACRS in the main analyses and excluded those seven persons with other secondary chronic headaches due to the low numbers and consequent statistical limitations.
The respondents with CPTH/CER had a higher proportion of subjects with headache frequency above the 75th percentile (≥90 headache days the past 3 months) and more severe disability than those with HACRS (Table
3).
Table 3
Descriptive statistics for respondents with chronic posttraumatic headache/cervicogenic headache vs. headache attributed to chronic rhinosinusitis. Number (%) unless stated otherwise
Age, mean (SD) | 38.9 (4.2) | 38.9 (3.8) | 0.97 |
Gender | | | 0.09 |
Female | 34 (72) | 34 (87) | |
Male | 13 (28) | 5 (13) | |
Education, highest attained | | | 0.37 |
< 11 years | 9 (19) | 6 (15) | |
11–15 years | 27 (57) | 25 (64) | |
> 15 years | 11 (24) | 8 (21) | |
Body mass index (kg/m2), mean (SD) | 27.6 (5.3)a
| 25.5 (4.5)b
| 0.08 |
Daily smoker | | | 0.61 |
No | 16 (36) | 16 (41) | |
Yes | 29 (64) | 23 (59) | |
Concomitant migraine | | | 0.23 |
No | 29 (62) | 19 (49) | |
Yes | 18 (38) | 20 (51) | |
Medication-overuse | | | 0.65 |
No | 24 (51) | 18 (46) | |
Yes | 23 (49) | 21 (54) | |
Number of headache days past 3 months | | | 0.001 |
< 90 (Q1-Q3) | 24 (53) | 32 (89) | |
≥ 90 (Q4) | 21 (47) | 4 (11) | |
MIDAS score (grade) | | | 0.038 |
0–20 (Little/no to moderate disability) | 9 (22) | 15 (45) | |
> 20 (Severe disability) | 31 (78) | 18 (55) | |
Epworth sleepiness scale score, mean (SD) | 6.8 (4.5) | 7.3 (4.2) | 0.60 |
Excessive daytime sleepiness (ESS score > 10) | | | 0.63 |
No | 37 (79) | 29 (74) | |
Yes | 10 (21) | 10 (26) | |
The overall prevalence of EDS was 23% (95% CI 16─33) among those with CPTH, CER or HACRS; 22% (95% CI 14─33) among women and 28% (95% CI 13─51) among men (Table
4). The prevalence of EDS in CPTH/CER without versus with co-occurrence of migraine was 24% (95% CI 12─42) and 17% (95% CI 6─39), respectively (
p = 0.54). The prevalence of EDS in HACRs without versus with co-occurring migraine was 16% (95% CI 6─38) and 35% (95% CI 18─57), respectively (
p = 0.17).
Table 4
Prevalence (%) of excessive daytime sleepiness (ESS >10) in people with secondary chronic headache
Men | 13 | 30.8 (12.7 to 57.6) | 5 | 20.0 (3.6 to 62.4) | 18 | 27.8 (12.5 to 50.9) |
Women | 34 | 17.6 (8.3 to 33.5) | 34 | 26.5 (14.6 to 43.1) | 68 | 22.1 (13.8 to 33.3) |
All | 47 | 21.3 (12.0 to 34.9) | 39 | 25.6 (14.6 to 41.1) | 86 | 23.3 (15.6 to 33.2) |
Headache diagnosis, medication overuse or the composite propensity score (age, gender, headache frequency and co-occurring migraine) was not associated with EDS in bivariate or multivariable analysis (Table
5).
Table 5
Odds for having EDS, defined as ESS > 10. Penalized maximum likelihood logistic regression
Headache type |
Posttraumatic/cervicogenica
| 47 | 1 | | | 45 | 1 | | |
Rhinosinusitis | 39 | 1.27 | (0.48 to 3.39) | 0.63 | 36 | 1.71 | (0.55 to 5.35) | 0.35 |
Medication-overuse |
Noa
| 42 | 1 | | | 41 | 1 | | |
Yes | 44 | 0.44 | (0.16 to 1.21) | 0.11 | 40 | 0.44 | (0.16 to 1.25) | 0.12 |
Propensity score (age, sex, headache frequency, migraine) | 81 | 0.77 | (0.07 to 8.33) | 0.83 | 81 | 0.35 | (0.02 to 5.53) | 0.45 |
Applying the χ
2-test in non-adjusted analyses, no significant differences (data not shown) were found in those with and without EDS depending on socio-demographics, body mass index, smoking, alcohol, caffeine, other sleep disorders, anxiety/depression, comorbidity of other disorders or medication use for other conditions.
Discussion
In this large population-based study almost one out of four subjects with secondary chronic headache reported EDS. The main finding was that the prevalence of EDS did not differ between those with CPTH/CEH and HACRS. Furthermore, medication-overuse, or the composite propensity score (age, gender, headache frequency and co-occurring migraine) was not associated with EDS in this population.
No previous study has investigated EDS for secondary chronic headache in the general population. The prevalence of EDS in men and women with secondary chronic headache corresponds to that for people with primary chronic headache in the general population (20.6% among women, 22.5% among men) and is comparable to data reported from the Norwegian general population (16.1% among women, 20.1% among men) [
11,
22]. Here, we did not include a directly comparable headache-free control group and caution is therefore warranted in this comparison. Also, due to the limited sample size in the present study, the risk of type 2 errors must be considered.
Little is known about the precise relationship between headache and sleep problems, when these occur concurrently. An association between EDS and different pain conditions has been reported [
2,
3]. Pain may disturb sleep and give rise to EDS, but sleep loss and EDS may also contribute to pain. Some of these secondary headaches are poorly understood, thus, further research is warranted [
23]. Studies suggest that CEH can be explained by local factors in the neck with dysfunction of the neck muscles and mechanical cervical spine pathology leading to limited cervical movements and projection of the pain [
24]. Headaches attributed to head trauma and whiplash trauma have instead been suggested to represent an interplay between the physical injury, neuroinflammation, psychological disturbances and emotional stress of the accident [
25,
26]. Finally, longstanding oedema of the nasal mucosa and rhinosinal inflammation result in chronic rhinosinusitis which may give chronic headache [
12]. The present study reported that CPTH/CEH and HACRS had similar prevalence of EDS despite these different headache forms probably being caused by different pathophysiological mechanisms. Therefore, it may be the complex burden of pain, more than the specific condition that is associated with EDS. Furthermore, the prevalence was comparable to that of two other different headache entities; chronic migraine and chronic tension-type headache [
11].
The population-based sample in the present study was large, and the high response rate should ensure that the sample was representative of the general population. Even though the sample size of secondary chronic headache may seem small, this is the largest sample of subjects with secondary chronic headache recruited from the general population.
The diagnostic criteria of CEH and HACRS have been discussed for many years [
12,
27]. When the study was conducted the more vague ICHD-II criteria for CEH were in use and HACRS was not recognized as a cause of chronic headache. Thus, to improve the diagnostic accuracy we used supplementary definitions. All patients diagnosed with CEH or HACRS in the present study fulfil the new ICHD-IIIβ criteria for these chronic headaches.
Face-to-face interviews by headache experts, as in the present study, provide more valid headache diagnoses than questionnaire-based studies [
28]. The ESS is a widely used, validated questionnaire for evaluating subjective daytime sleepiness, and the score is associated with clinically important outcomes, such as cognitive impairment, cardiovascular mortality, and injuries [
29,
30].
The 30–44 years age range in our study was chosen in order to ascertain a general population sample without much co-morbidity of non-headache disorders. Because EDS varies with age, our findings may not be generalizable to younger or older populations. The study lacked data on sleep quality and sleep duration that may be associated with sleepiness in headache [
5,
6,
8,
9].
The overall sample size limited the number of variables that could be analyzed as potential confounders, and this also lead us to dichotomize many variables for use in the analyses. Also, due to the small number in the present study, the risk of type 2 errors must be considered. Finally, the cross-sectional design in the present study does not permit any conclusions about causality.
In conclusion, there was no difference in the prevalence of EDS between subgroups of different secondary chronic headache diagnoses.