Self-help interventions for depressive disorders and depressive symptoms: a systematic review

There has been one small randomised controlled trial (RCT) [20]. A total of 35 adults with mild to moderate major depressive disorder received either placebo or 375 mg of aqueous extract of borage flowers daily for 6 weeks. By week 4 there was a small significant difference in levels of depression symptoms between the two groups, with lower levels in the borage group. Results at week 6 were similar but no longer statistically significant.

Three RCTs have evaluated acetyl-L-carnitine supplementation in individuals with dysthymia [23‐25]. Of these trials, 2 were in 46 or 52 older adults (aged 60 to 80 years) and compared 3 g daily doses of acetyl-L-carnitine with placebo over 60 days. Those taking acetyl-L-carnitine showed significantly improved depression symptoms compared with those taking placebo. The other trial compared 1 g daily dosage of acetyl-L-carnitine with 50 mg amisulpride in 193 participants with dysthymia and found both groups had improved depression symptoms over 3 months and there was no significant difference in improvement between groups [25].

A double-blind RCT evaluated the effect over days of carnitine on depressed mood [26]. A total of 400 adult females received either a placebo, 2 g carnitine, 1.6 g lecithin, or both lecithin and carnitine for 3 days. Carnitine supplementation had no effect on depressed mood.

A trial of 113 adults with atypical depression who took either 400 to 600 μg chromium picolinate or placebo for 8 weeks found no significant difference in the reduction of depression symptoms or rates of response [28]. However, a subgroup analysis found that adults who had high carbohydrate craving showed a greater response to chromium than placebo.

Two RCTs in 104 healthy young adults and 93 older adults of 120 mg ginkgo daily for 12 weeks showed no effect on depressed mood [31].

One RCT has examined ginseng's effects on mood over months in healthy adults. In all, 83 participants took either 200 mg ginseng, 400 mg ginseng or placebo daily for 60 days [33]. Ginseng supplementation had no effect on depressed mood.

One small double-blind RCT has compared lavender with an antidepressant in adults with depressive disorders [34]. A total of 45 adults with major depression participated in a 4-week trial where they received 60 drops of a lavender tincture plus placebo tablet, 100 mg imipramine plus placebo drops, or lavender plus imipramine. Although depression symptoms improved significantly in all groups, the lavender group improved significantly less than the imipramine group, and there was no placebo control group to rule out placebo effects.

One double-blind RCT has examined the effect over days of lecithin on depressed mood [26]. A total of 400 adult females received either a placebo, 1.6 g lecithin (phosphatidylcholine), 2 g carnitine, or both lecithin and carnitine for 3 days. Lecithin supplementation had no effect on depressed mood.

An RCT of 53 adults with subsyndromal SAD and/or weather-associated syndrome who took 2 mg slow-release melatonin in the evening for 3 weeks found no significant difference in atypical depression symptoms between melatonin and placebo [36].

Although there have been several reviews of omega 3 fatty acids for depression [37, 38], only one study has evaluated omega 3 as a single treatment for depression in sufficient participants [39]. A double-blind RCT of 35 depressed adults with low fish intake who took 2 g DHA or placebo daily for 6 weeks found that omega 3 supplementation was no better than placebo in reducing depression symptoms.

A single RCT of 49 healthy adults examined the effect on depressed mood of supplementation of 4 g fish oil (containing 1,600 mg EPA and 800 mg DHA), or placebo for 35 days [40]. Depressed mood reduced significantly in the omega 3 group but not in the placebo group.

Both a recent systematic review [41] and a meta-analysis [42] have found SAMe helpful for depressive disorders. The systematic review was restricted to trials that passed a quality assessment. Those included were five uncontrolled trials and two RCTs. Despite differences in doses, route of administration (oral, intramuscular, intravenous) and comparison or control treatments, SAMe had a consistent positive effect over weeks or months. An additional RCT was included after the review was completed, which found that the efficacy of 1,600 mg/day oral SAMe or 400 mg/day intramuscular SAMe was not significantly different from 150 mg/day of imipramine. The meta-analysis included 28 trials and found greater improvement with SAMe than with placebo (global effect size ranging from 17% to 38% depending on definition of response), and no difference in outcomes between treatment with SAMe and standard tricyclic antidepressants.

Four double-blind RCTs have examined the effect of saffron (stigma) or Crocus sativus petals on depressed adults. Two trials each with 40 adults compared saffron stigma (30 mg daily), with fluoxetine (20 mg) [44] or with placebo [45] for 6 weeks. Saffron significantly reduced depression symptoms more than placebo, and there was no significant difference in efficacy between saffron and fluoxetine. Similarly, 30 mg extracts from the petals of Crocus sativus have also shown efficacy similar to 20 mg fluoxetine [46] and greater efficacy than placebo [47] in trials of 40 adults.

Two trials have examined selenium intake and depressed mood in non-depressed adults. A double-blind crossover trial found daily supplementation of 100 μg selenium in 50 adults significantly improved depressed mood over 5 weeks (compared to placebo) [48, 49] and a RCT found no effect of a range of dosages of selenium supplementation in 448 older adults over 6 months [50].

Several systematic reviews and meta-analyses examining St John's wort for depression have been published in recent times. A systematic review of these reviews [51] concluded that although review methodologies have varied, St John's wort has consistently been found to be beneficial for mild to moderate depression compared to placebo, although the degree of benefit has varied between reviews. Comparisons against antidepressants have usually found no difference in benefit. The most recent Cochrane review of St John's wort for depression, published after the above mentioned review was completed, paints a more complex picture [52]. The review was restricted to double blind RCTs of at least 4 weeks duration in adults with depressive disorders. A total of 37 trials involving 4,925 participants met inclusion criteria, and the majority were judged reasonable to good quality. Pooled results from 24 trials found that St John's wort was overall superior to placebo (response rate ratio 1.55, 95% confidence interval (CI) 1.42 to 1.70), and pooled results from 13 trials found no difference between St John's wort and older or newer antidepressants (response rate ratio 1.01, 95% CI 0.93 to 1.10). However, results from the studies comparing St John's wort to placebo were heterogeneous, with metaregression analyses leading to the conclusion that St John's wort showed greater benefits for individuals with mild depression. A variety of preparations of St John's wort were used and daily doses ranged from 240 mg to 1,800 mg. St John's wort caused fewer negative side effects than older antidepressants, and may have caused slightly fewer negative side effects than newer antidepressants. Use of St John's wort is not without risk however, as it has the potential to make other medications (such as immune suppressants, oral contraceptives and anticoagulants) less effective by increasing their rate of metabolism, and can also interact with selective serotonin reuptake inhibitors to cause a toxic reaction [51].

A double-blind RCT in 117 healthy young adult females of 50 mg thiamine or placebo daily for 2 months found that supplementation had no effect on depressed mood [56].

Although a systematic review has examined vitamin B₆ for depression [57], all trials evaluated vitamin B₆ in combination with another treatment or used it only with hormone-related depression.

A single double-blind RCT has been carried out in 211 young, middle-aged and older female adults of 75 mg vitamin B₆, 750 μg folate, 15 μg vitamin B₁₂ or placebo for 5 weeks. Vitamin B₆ supplementation had no effect on depression symptoms or depressed mood [53].

Two double-blind RCTs have tested the effect of supplementation of vitamin B₁₂ on depression symptoms in healthy adults. A weekly injection of 1 mg B₁₂ for 4 weeks in 134 elderly adults who showed signs of vitamin deficiency did not reduce depression symptoms significantly more than placebo [58]. Similarly, B₁₂ had no effect on depression symptoms or depressed mood when taken daily in a dose of 15 μg for 5 weeks in a double-blind RCT of 211 young, middle-aged and older female adults [53].

Although a systematic review examined folate for depression [59] no RCTs were included that examined folate on its own as a treatment for people who were depressed without other medical conditions.

A double-blind RCT in 211 young, middle-aged and older female adults of 750 μg folate, 15 μg vitamin B₁₂, 75 mg vitamin B₆ or placebo for 5 weeks found folate supplementation had no effect on depression symptoms or depressed mood [53].

A double-blind RCT in 81 healthy young adults who took 3,000 mg sustained-release vitamin C or placebo for 14 days found depression symptoms significantly decreased in the vitamin C but not the placebo group [60]. However, the decrease was very small.

Three RCTs have examined vitamin D supplementation in healthy adults. In all, 250 middle-aged and older adult females took 377 mg calcium plus 400 IU vitamin D daily, or 377 mg calcium on its own for a year [61]. Depressed mood was assessed four times over the year, with vitamin D showing no effect. A 5-day trial in 44 adults of either vitamin D (400 IU or 800 IU) plus vitamin A (9,000 IU or 8,000 IU) versus 10,000 IU vitamin A only, found that vitamin D improved positive mood, but did not change negative mood [62]. Finally, a large 6-month trial of 2,117 women aged over 70 years compared supplementation with vitamin D (800 IU) plus calcium (1,000 mg) with no supplementation. No significant difference was found in depressed mood between the two groups [63].

Seven double-blind RCTs have examined the effects of multivitamin supplementation on depressed mood or symptoms in healthy non-depressed adults. A total of 120 young adults took a placebo or a multivitamin that contained 10 times the US recommended daily amount except for vitamin A (3,334 IU vitamin A, 14 mg B₁, 16 mg B₂, 180 mg B₃, 22 mg B₆, 2 mg B₇, 0.03 mg B₁₂, 600 mg vitamin C, 100 mg vitamin E and 4 mg folate), for 12 months [55]. Supplementation had no effect on depressed mood after 3 or 12 months. A similar trial in 126 older adults of supplementation of the same multivitamin combination and dosage for 24 weeks also had no effect on depressed mood [54]. A trial in 95 adults of Pharmaton capsules (a supplement containing vitamins, minerals, trace elements and ginseng) for 8 weeks showed no effect on depressed mood [64]. A larger follow-up trial in 313 adults of the same supplement for 8 weeks also showed no effect on depressed mood. However, a subgroup analysis found that participants who were dieting had a greater improvement in depressed mood if they were taking the supplement than if they were taking the placebo [65]. A trial in 77 adult males of Berocca Performance supplementation (containing vitamins B₁, B₂, B₃, B₅, B₆, B₇, B₁₂, folate, C, and calcium, magnesium, zinc) for 28 days found that Berocca was no better than placebo at reducing depression symptoms [66]. Finally, a trial of antioxidant supplementation (consisting of 12 mg/day β-carotene, 400 mg/day α-tocopherol, and 500 mg/day vitamin C) in 185 older adults for 12 months also showed no effect on depressed mood [67].

A review of studies, including several RCTs that evaluated caffeine consumption in healthy adults generally concluded that caffeine temporarily improves feelings of wellbeing, energy and mood [69]. However, caffeine use is widespread, study participants are typically not allowed caffeine before the experiment, and withdrawal from caffeine often involves depressed mood [70]. Therefore some argue that the mood benefits are due to a reversal of withdrawal symptoms [71]. Others disagree with this interpretation and argue that positive effects of caffeine on mood have been found when participants were not in caffeine withdrawal [69].

A crossover trial has compared the effects on depressed mood over hours of a carbohydrate-rich, protein-poor meal with a protein-rich, carbohydrate-poor meal in 16 adults with seasonal affective disorder and 16 non-depressed adults [73]. Participants ate each meal on separate days, with the order of meals randomised. Results are difficult to interpret due to order effects. Both types of meals reduced depressed mood when eaten first, but when they were eaten second, the carbohydrate-rich meal decreased depressed mood while the protein-rich meal increased it.

Three RCTs have examined the effect over minutes or hours of a carbohydrate-rich, protein-poor meal on depressed mood. One trial found depressed mood decreased across all participants after a carbohydrate-rich meal [74], one trial found depressed mood did not increase under stressful conditions in high-stress prone individuals after the consumption of a carbohydrate-rich meal compared with a protein-rich meal [75], and one trial found no significant difference in depressed mood between a carbohydrate-rich and a protein-rich meal [76]. Studies varied in the type of participants (young adults, older adults, obese adults), time of day when meal was eaten (lunch time, early or mid afternoon), type of meal (such as cake or liquid) and the carbohydrate, fat and protein proportions of meals classified carbohydrate-rich and protein-rich.

A quasi-RCT compared autogenic training with psychotherapy and delayed treatment in 55 adults with depressive disorders [77]. Participants undertook weekly group autogenic training sessions plus twice-daily practice or weekly individual psychotherapy for 10 weeks. Depression symptoms in the autogenic training group improved significantly more than in the delayed-treatment control group, but significantly less than in the psychotherapy group.

One RCT allocated 134 adults with minor psychological problems to 3 months of individual autogenic training with a therapist plus twice-daily practice or a delayed-treatment group [78]. The autogenic training group had significantly improved depressed mood after 3 months, whereas the control group showed no change.

Several meta-analyses have evaluated the helpfulness of bibliotherapy for depression. A recent meta-analysis pooled results from 17 trials (16 RCTs) which compared bibliotherapy with a delayed treatment control group [85]. Trial participants varied in age from adolescents to the elderly and usually had mild to moderate depression without other physical or mental health problems. Trials lasted for 7 weeks on average. The meta-analysis found bibliotherapy more effective than controls (d = 0.77, 95% CI 0.61 to 0.94). Another meta-analysis of six RCTs that used the book Feeling good also found a large difference in depression over 4 weeks in favour of bibliotherapy over delayed treatment (standardised mean difference = -1.36, 95% CI -1.76 to -0.96) [81]. However, the trials were small and of limited quality. An earlier meta-analysis of four RCTs, which compared bibliotherapy with individual therapy, found no significant difference in depression [86]. The trials used different kinds of bibliotherapy, had small samples, and lasted between 6 and 11 weeks.

A meta-analysis of 5 RCTs examined the effects of internet-based CBT on depression over weeks or months in a total of 1,982 adults recruited from a mix of clinical and community sources [91]. The meta-analysis showed an overall small difference in depression between the internet CBT and control groups (fixed effects analysis d = 0.27, 95% CI 0.15 to 0.40; mixed effects analysis d = 0.32, 95% CI 0.08 to 0.57). The trials were of reasonable to good quality and had no professional involvement in four. Similarly, another review of eight RCTs found that computerised CBT without professional involvement had a small effect on depression, but that computerised CBT with professional involvement had a bigger effect, similar to that achieved in face to face CBT [92]. The author proposed that the smaller effect on depression of unsupervised computerised CBT could be due to low completion rates caused by the absence of a motivating professional. Only one RCT has examined the use of a depression information website [93]. This intervention was found to produce significantly greater change in depression than a control condition and was not significantly different from web-based CBT.

A controlled trial in 59 adolescent males of MoodGYM, an internet-based CBT program, compared 5 weekly sessions of in-class use of MoodGYM with the usual personal development class scheduled at that time [94]. There was no significant difference in change in depression symptoms between the two groups. However, compliance was low, with only 40% completing at least half of the MoodGYM program.

A number of experiments have been conducted on the effects of distraction on depressed mood over minutes, in both clinically depressed people and people with a high score on a depression symptom scale [96‐103]. A number of distraction tasks have been used, such as thinking about and visualising a series of neutral external things (for example, the shape of the African continent or the layout of a typical classroom), describing pictures, playing a board game, or thinking about broad social issues. Many of these experiments have compared distraction to a rumination task which involves focusing on current feelings and personal characteristics, such as 'your feelings right now and why you are feeling this way'. The generally consistent finding has been that rumination increases or maintains depressed mood, whereas distraction reduces depressed mood. The few studies that compared distraction with a control (such as sitting quietly or receiving no instructions from experimenters) also show that distraction is better at reducing depressed mood [104‐107].

Other studies have experimentally induced depressed mood in non-clinically depressed participants before applying distraction [107‐113] and have also typically found that distraction reduces depressed mood.

Five RCTs have evaluated the effects of meditation on depressed mood or symptoms in non-clinically depressed individuals, with inconsistent results. An RCT in 73 elderly of transcendental meditation versus other mental relaxation or concentration tasks or waitlist found no significant difference in depression between groups after 12 weeks [114]. An RCT in 42 young adults that compared mindfulness meditation with guided visual imagery for 3 weeks found that neither intervention had an effect on depressed mood [115]. In contrast to these two trials, three RCTs found an effect. An RCT in 150 adults who participated in a week-long Buddhist meditation retreat found that the meditation group had significantly reduced depression symptoms compared with the delayed treatment control group [116]. An RCT in 61 adults who were assigned to 1 of 2 meditation groups or a control group, found that those assigned to the group using an Indian Vedic mantra (hypothesised to be particularly helpful for depression) had a significantly greater reduction in depression symptoms after 28 days of meditating, compared with either the control group or the group using a mantra composed of meaningless Sanskrit syllables [117]. Finally, an RCT that induced a depressed mood in 177 young adults found that a short mindfulness meditation significantly improved mood more than a distraction or rumination task [112].

Nine RCTs have evaluated progressive muscle relaxation training in adolescents or adults with depressive disorders [118‐126]. The number of participants undergoing relaxation training varied between 8 and 43, the number of relaxation sessions varied from 5 to 40, and the training was delivered by trained persons in 7 of these trials. An unpublished meta-analysis of four of these trials [120, 123, 124, 126] that compared relaxation training with wait-list or minimal treatment control groups found significantly lower depression scores overall after treatment in the relaxation group (d = -0.66, 95% CI -1.07 to -0.25). However, a meta-analysis of results from six trials [120‐125] comparing relaxation with psychological treatment found that relaxation was significantly less helpful in reducing depression than psychological therapy (d = 0.52, 95% CI 0.25 to 0.79).

Five RCTs have compared progressive muscle relaxation training with a placebo or non-treatment control in non-depressed individuals [127‐131]. All found that relaxation was no better than the control in reducing depression symptoms or depressed mood. These trials varied in the age of participants (from children to older adults), duration of the intervention (6 to 11 weeks), length of relaxation sessions (5 min to 1.5 h), and whether the training was administered in a group or by the participant at home.

The most recently published meta-analysis of exercise for depression restricted included trials to those with adults or older adults who were clinically depressed [132]. Results were pooled from 11 RCTs involving 513 participants that compared exercise to a control condition (waitlist, placebo, low-intensity exercise or health education). Exercise interventions varied in frequency from between two to four times weekly, in duration between 20 and 45 min, and in intensity between unspecified and 70–85% maximum heart rate, for up to 12 weeks. The meta-analysis found an overall very large difference in depression between the two groups, with exercise being more effective (d = 1.42, 95% CI 0.92 to 1.93). Preliminary subgroup analyses indicated that anaerobic exercise may be as effective as aerobic exercise. A systematic review examining exercise specifically in older adults found 5 RCTs involving 318 older adults with depression (diagnosed or high level of symptoms), varying between 6 and 16 weeks in duration [133]. Compared to controls, depression symptoms were significantly lower in the exercise condition (both aerobic and anaerobic) in four of the five trials, although trials were not of high quality. Exercise has also been systematically reviewed as an intervention in children and young people with depressive disorders [134]. Three small trials were found, involving 81 participants. These were of low to moderate quality and all indicated no significant difference in outcome between exercise and various control conditions. The authors concluded that the evidence base was too scarce to determine the effect of exercise on depression in children and young people.

A non-systematic review of trials evaluating the effect on depression symptoms of aerobic exercise in non-depressed adults found that older lower quality studies had mixed results, but more recent RCTs generally find no reduction in depression symptoms [135]. A systematic review of exercise for depression in non-depressed older adults found 5 RCTs involving 766 participants [133]. Trials lasted between 12 weeks and 12 months. Three trials comparing aerobic exercise with control interventions had mixed results, whereas two trials comparing anaerobic exercise with controls found no significant difference in reduction of depression symptoms. A systematic review of exercise for depression in non-depressed young people found exercise more effective than no intervention in 5 low quality trials involving 145 participants [134]. Conversely, there was no effect of exercise found in 2 low quality trials comparing exercise with low intensity exercise (182 participants) and 2 low to moderate quality trials comparing it to psychosocial interventions (161 participants). Researchers have also investigated the effects over minutes of a single session of exercise on depressed mood. A selective review found 17 trials in non-depressed adolescents or adults where a variety of exercise (aerobic dance, yoga, jogging, rock climbing, swimming, tai chi and walking), ranging in duration from 10 to 80 min, had made improvements to depressed mood in participants [136]. The review did not indicate whether trials were controlled. The authors noted that positive effects depend upon complex interactions between participant characteristics (such as whether they found the exercise enjoyable), exercise mode (such as whether it is competitive or non-competitive), and exercise practice conditions (such as intensity and duration).

Two RCTs have examined humour's effect on depressed mood after exposure to stress or a negative mood induction. A trial with 38 young adults who underwent a depressed mood induction found that only listening to a humorous tape restored mood to pre-experimental levels, compared with a neutral tape or no tape [139]. An RCT in 80 males found that those who produced a humorous narration instead of a serious narration to a stressful silent film had significantly lower levels of depressed mood, although the effect did not last beyond 15 min [138]. The only trial to evaluate effects lasting longer than minutes was an RCT in 61 nursing home residents that examined the effect of humorous weekly group sing-a-longs on depression symptoms [140]. Compared to residents in control homes who received no intervention, those in the sing-a-long groups had significantly reduced depression symptoms after 4 weeks on one measure, but not on another. However, it is not clear whether the humour or other aspects of the intervention (such as social interaction or singing) were responsible for the effect.

Two RCTs have examined the effects of live-in birds assigned individually to older adults. Half of 40 older adult residents of skilled rehabilitation units received a caged budgerigar in their room for 10 days [141]. The group who received a bird had significantly reduced depression scores at the end of the trial, although the authors noted this result might have been caused by an increase in human visitors to see the bird. A larger, better designed trial also had a similar result. A total of 144 nursing home residents were given a canary, a plant or nothing to look after in their rooms for 3 months [142]. Depression symptoms significantly improved in the group assigned canaries, but not in the other two groups.

A meta-analysis of RCTs of activity scheduling for depression in adults found clear indications that it is effective [143]. A total of 10 studies compared activity scheduling with a control (usually a delayed treatment) and there was an overall large difference in depression, favouring activity scheduling (d = 0.87, 95% CI 0.60 to 1.15). A total of 14 studies compared activity scheduling with other psychological treatments (usually cognitive therapy), and overall there was no difference in depression after treatment (d = 0.13, 95% CI -0.05 to 0.30). Trials were generally small and not of the highest quality. However, these trials only examined activity scheduling as a treatment from a professional. Other factors, such as the therapeutic relationship, ritual of the therapy, or even other treatment components in particular trials, such as social skills training, may play a role in treatment outcome. Therefore, it is difficult to generalise these findings to a self-help method of activity scheduling.

An RCT of 65 non-depressed young adults had 3 groups: a monitor only control group, who monitored their daily activities and mood; a behaviour group, who additionally increased the number of activities found pleasurable; and a cognitive/behaviour group, who in addition to increasing pleasurable activities, focused on the positive aspects of the pleasant activities and the benefits of participating in them [144]. After 2 weeks, depression scores significantly decreased for the monitor group and the cognitive/behaviour group, but not for the behaviour group. This finding was interpreted as support for the view that cognitive processing is required in addition to activity scheduling for an antidepressant effect, but this does not account for the decrease in depression shown in the monitor group.

One RCT in 88 Christian adults found practicing the Jesus prayer ('Lord Jesus Christ, have mercy on me') for 10 min daily for 30 days lowered depression scores significantly more than a non-treatment control group [145].

One crossover trial with order randomised has evaluated the effects over minutes of qigong on depressed mood [146]. A total of 15 older adults recruited from existing qigong classes participated in a session of both qigong and brisk walking. Level of depressed mood did not significantly change after either session.

Reviews of the efficacy of sleep deprivation for depressive disorders conclude that about 60% of depressed individuals improve after sleep deprivation [147, 148]. The degree of symptom change ranges from complete remission to worsening in a minority. The effect is delayed in some individuals who only respond following sleep the next day. The evidence is unclear, but partial sleep deprivation may be as effective as total sleep deprivation [147]. Although the antidepressant effect is rapid, it typically does not last, with 50–80% of responders suffering a complete or partial relapse following recovery sleep. Researchers have attempted to prevent relapse with other treatments such as antidepressant drugs, shifting of sleep time or light therapy, which show promise for reducing the risk of relapse.

One RCT in 40 males found a significant increase in depressed mood after 24 h of wakefulness as compared to controls who had a typical night's sleep [149].

Two RCTs have compared tai chi with different forms of exercise or relaxation. A total of 96 healthy adult tai chi practitioners participated in 1 h of tai chi, brisk walking, tai chi meditation or neutral reading after being subject to experimentally induced emotional or mental stress [151]. All activities significantly improved depressed mood. Another trial compared a 16-week program of tai chi against low or moderate intensity walking, low intensity walking with relaxation, and no treatment in 135 adults [152]. Depressed mood significantly improved in women in the tai chi group compared to those in the control, but changes in depressed mood in men did not differ significantly between the different groups.

A recent systematic review of randomised controlled trials of yoga for depression found five trials to review [153]. The studies varied in the type of yoga studied (such as Iyengar, Shavasana, and Sudarshan Kriya Yoga), severity of depression (mild to severe), number of participants per yoga group (10–25), and length of intervention (3 days to 5 weeks), and participants were all under 50 years. Nevertheless, the authors concluded that yoga for depressive disorders is potentially beneficial, but that further investigation is needed.

Three RCTs have evaluated the effects over months of yoga classes on depressive symptoms or depressed mood, with inconsistent results. Two trials in older adults of 60–90 min yoga sessions once or twice a week for 16 weeks to 6 months found no effect on depressed mood or symptoms relative to controls [154, 155]. However one shorter trial of 6 weeks in adults found depressed mood significantly improved in the yoga group compared with a wait-list control group [156].

One RCT has examined aromatherapy's effects over minutes on depressed mood in non-clinically depressed adults. A total of 73 adults were exposed to water or essential oils of lavender or rosemary for 10 min whilst they completed a stressful mental task. At the end of the task there was no significant difference in depressed mood between groups [158].

An RCT in 40 adults found no effect on depressed mood of a 10-min immersion in a spa bath with either the whirlpool motor on or off [160].

Two recent meta-analyses have been carried out. The first examined light therapy for depression and SAD in non-geriatric adults over days or weeks [162]. Included studies were RCTs of a reasonably high standard, with light therapy groups receiving adequate doses of light exposure. Three studies were included in the meta-analysis of light therapy for depression, eight for light therapy for SAD, and five for dawn simulation for SAD. The meta-analyses revealed a large effect of light therapy (d = 0.84, 95% CI 0.60 to 1.08) and dawn simulation on SAD (d = 0.73, 95% CI 0.37 to 1.08), compared with placebo, and a medium-sized effect of light therapy on depression (d = 0.53, 95% CI 0.18 to 0.89). Another meta-analysis looked exclusively at light therapy for non-seasonal depression and applied broader inclusion criteria for trials [163]. A total of 18 RCTs were analysed, however only 2 used light therapy as the only treatment. Pooling results from these two studies showed that light therapy was beneficial when using a fixed effects analysis, but the result did not reach significance using a random effects model. A systematic review of light therapy for depressed children and adolescents also concluded that limited evidence suggests it is helpful for winter depression, but not for non-seasonal depression [19].

Four RCTs have evaluated light therapy in non-clinically depressed individuals over days or weeks, with mixed findings. Trials with participants who experienced winter difficulties (subsyndromal SAD) found light therapy helpful for depressed mood or symptoms [164, 165]. Light therapy doses were 2,500 lux for 2–5 h in the morning or split over both morning and evening, Trials with participants who had no winter difficulties generally did not find light therapy helpful [164‐167] and some of these participants experienced negative effects, such as irritability, after light therapy [166].

Two RCTs have evaluated the effects over minutes of massage in people with depressive disorders. One trial was of a 30-min massage in children or adolescents with dysthymia [169], and one was of a 20-min massage in depressed pregnant women [118]. Both trials compared massage with a form of relaxation and found massage significantly reduced depressed mood compared with relaxation. These trials also evaluated the effects of multiple doses of massage. Changes in depressed mood or symptoms were examined over the duration of each trial (lasting 5 days and 16 weeks respectively), with both finding a significant reduction in the massage group compared with controls.

Four RCTs have evaluated the effects over minutes of massage on non-depressed adults compared to some control intervention. The results have been variable. One RCT found massage produced greater effects than reading [170], however two RCTs found no significant difference from relaxation [171, 172] and one found no difference from resting [173]. Massages were restricted to the upper body and were 10 to 30 min long. One RCT has evaluated multiple doses of massage, but only against relaxation therapy. A total of 50 adults were given a 15-min massage or were told to tighten and relax their muscles twice a week for 5 weeks. Depressed mood in both the massage group and the relaxation control group significantly improved [171].

Listening to music (both classical and modern) has frequently been used in experimental settings to induce particular moods in participants. A meta-analysis of these studies concluded that music is a moderately effective method of inducing temporary depressed or elated mood in experimental settings with non-depressed individuals [175]. Only one RCT has examined the effects of listening to music over weeks [176]. A total of 102 adult female nurses participated in a 6-week trial where they were instructed to listen to 20 min of music self-selected to be stress reducing three times a week, perform 20 min of self-selected aerobic exercise three times a week or maintain their usual exercise and stress-reduction activities. Listening to music did not reduce depression symptoms significantly more than the control group.

One RCT in participants with seasonal affective disorder found significantly greater reduction in depression symptoms over weeks with 30 min daily exposure to high density negative ionisation (4.5 × 10¹³/s flow rate) compared with a placebo of low density negative ionisation [178].

One RCT [167] compared exposure to high density (4.5 × 10¹⁴/s) negative ion generators, bright light, music or low density (1.7 × 10¹¹/s) negative ion generators (placebo) for 30 min in 118 non-depressed adults. The high density negative ions significantly decreased depressed mood compared with placebo. Another study of depressed mood in non-depressed adults found that exposure to high concentrations of negative ions significantly decreased depressed mood compared with exposure to low concentrations of negative ions. However, depressed mood was significantly increased in those who were experimentally manipulated to feel angry and exposed to high negative ion concentrations, compared with those who were also experimentally manipulated to feel angry but were exposed to low negative ion concentrations [179].

Effects over weeks were examined in an RCT involving 61 nursing home residents who participated in humorous weekly group sing-a-longs [140]. Compared to residents in control homes who received no intervention, those in the sing-a-long groups had significantly reduced depression symptoms after 4 weeks on one measure, but not on another. However, it is not clear whether the singing or other aspects of the intervention (such as humour or social interaction) were responsible for the effect.