Bright Light Therapy in the Morning or at Mid-Day in the Treatment of Non-Seasonal Bipolar Depressive Episodes (LuBi): Study Protocol for a Dose Research Phase I / II Trial

Circadian light therapy and light dose for depressed young people: a systematic review and meta-analysis

Background

Empirical evidence has shown that light therapy (LT) can reduce depression symptoms by stimulating circadian rhythms. However, there is skepticism and inconclusive results, along with confusion regarding dosing. The purpose of this study is to quantify light as a stimulus for the circadian system and create a dose-response relationship that can help reduce maladies among adolescents and young adults (AYAs). This will provide a reference for light exposure and neural response, which are crucial in the neuropsychological mechanism of light intervention. The study also aims to provide guidance for clinical application.

Methods

The latest quantitative model of CLA (circadian light) and CSt,f (circadian stimulus) was adopted to quantify light dose for circadian phototransduction in youth depression-related light therapy. Articles published up to 2023 through Web of Science, Cochrane Library, Medline (OVID), CINAHL, APA PsycINFO, Embase, and Scholars were retrieved. A meta-analysis of 31 articles (1,031 subjects) was performed using Stata17.0, CMA3.0 (comprehensive meta-analysis version 3.0) software, and Python 3.9 platform for light therapy efficacy comparison and dose-response quantification.

Results

Under various circadian stimulus conditions (0.1 < CSt,f < 0.7) of light therapy (LT), malady reductions among AYAs were observed (pooled SMD = -1.59, 95%CI = -1.86 to -1.32; z = -11.654, p = 0.000; I2 = 92.8%), with temporal pattern (p = 0.044) and co-medication (p = 0.000) suggested as main heterogeneity sources. For the efficacy advantage of LT with a higher circadian stimulus that is assumed to be influenced by visualization, co-medication, disease severity, and time pattern, sets of meta-analysis among random-controlled trials (RCTs) found evidence for significant efficacy of circadian-active bright light therapy (BLT) over circadian-inactive dim red light (SMD = -0.65, 95% CI = -0.96 to -0.34; z = -4.101, p = 0.000; I2 = 84.9%) or circadian-active dimmer white light (SMD = -0.37, 95% CI = -0.68 to -0.06; z = -2.318, p = 0.02; I2 = 33.8%), whereas green-blue, circadian-active BLT showed no significant superiority over circadian-inactive red/amber light controls (SMD = -0.21, 95% CI = -0.45 to 0.04; z = -2.318, p = 0.099; I2 = 0%). Overall, circadian-active BLT showed a greater likelihood of clinical response than dim light controls, with increased superiority observed with co-medication. For pre-to-post-treatment amelioration and corresponding dose-response relationship, cumulative duration was found more influential than other categorical (co-medication, severity, study design) or continuous (CSt,f) variables. Dose-response fitting indicated that the therapeutic effect would reach saturation among co-medicated patients at 32-42 days (900-1,000 min) and 58-59 days (1,100-1,500 min) among non-medicated AYAs. When exerting high circadian stimulus of light therapy (0.6 < CSt,f < 0.7), there was a significantly greater effect size in 1,000-1,500 min of accumulative duration than <1,000 or >1,500 min of duration, indicating a threshold for practical guidance.

Limitations

The results have been based on limited samples and influenced by a small sample effect. The placebo effect could not be ignored.

Conclusions

Although the superiority of LT with higher circadian stimulus over dimmer light controls remains unproven, greater response potentials of circadian-active BLT have been noticed among AYAs, taking co-medication, disease severity, time pattern, and visual characteristics into consideration. The dose-response relationship with quantified circadian stimulus and temporal pattern had been elaborated under various conditions to support clinical depression treatment and LT device application in the post-pandemic era.

Preventive effect of morning light exposure on relapse into depressive episode in bipolar disorder

OBJECTIVE

Light therapy has been suggested to have a curative effect on bipolar depression; however, preventive effects of light exposure on depressive episodes remain unclear. This study evaluated whether daytime light exposure in real-life situations was associated with a preventive effect on relapse into depressive episodes in patients with bipolar disorder.

METHODS

This prospective, naturalistic, observational study was conducted in Japan between August 2017 and June 2020. Outpatients with bipolar disorder were objectively evaluated for daytime light exposure over 7 consecutive days using an actigraph that could measure ambient light at baseline assessment and then assessed at 12-month follow-up for relapse into mood episodes.

RESULTS

Of 202 participants, 198 (98%) completed follow-up at 12 months and 78 (38%) experienced relapse into depressive episodes during follow-up. In a Cox proportional hazards model adjusting for potential confounders, a longer time above 1000 lux at daytime was significantly associated with decrease in relapse into depressive episodes (per log min; hazard ratio, 0.66; 95% confidence interval, 0.50-0.91). In addition, a higher average illuminance and longer time above 1000 lux in the morning exhibited a significant decrease in relapse into depressive episodes (per log lux and per log min; hazard ratio, 0.65 and 0.61; 95% confidence interval, 0.49-0.86 and 0.47-0.78, respectively). The association between daytime light exposure and relapse into manic/hypomanic/mixed episodes was not significantly different.

CONCLUSION

A significant association was observed between increased daytime light exposure, mainly in the morning, and decreased relapse into depressive episodes.

Biological rhythms and chronotherapeutics in depression

Depressive syndromes are frequent and heterogeneous brain conditions with more than 90% of patients suffering from sleep complaints. Better characterizing this "sleep" domain may allow to both better treat acute episodes with existing chronotherapeutics, but also to prevent the manifestation or recurrences of mood disorders. This work aims to i) review theoretical and fundamental data of chronotherapeutics, and ii) provide practical recommendations. Light therapy (LT) can be used as a first-line monotherapy of moderate to severe depression of all subtypes. LT can be also used as a combination with antidepressant to maximize patients' response rates, which has a clear superiority to antidepressant alone. Sleep deprivation (SD) is a rapid and powerful chronotherapeutic with antidepressant responses within hours in 45-60% of patients with unipolar or bipolar depression. Different strategies should be combined to stabilize the SD antidepressant effect, including concomitant medications, repeated SD, combination with sleep phase advance and/or LT (triple chronotherapy). Melatonin treatment is of interest in remitted patients with mood disorder to prevent relapses or recurrences, if a complaint of insomnia, poor sleep quality or phase delay syndrome is associated. During the acute phase, melatonin could be used as an adjuvant treatment for symptoms of insomnia associated with depression. The cognitive behavioral therapy for insomnia (CBT-I) can be recommend to treat insomnia during euthymic phases. The Interpersonal and social rhythm therapy (IPSRT) is indicated for the acute treatment of bipolar depression and for the prevention of mood episodes. Chronotherapeutics should always be associated with behavioral measures for healthy sleep.

Adjunctive bright light therapy for treating bipolar depression: A systematic review and meta-analysis of randomized controlled trials

OBJECTIVES

Bright light therapy (BLT) was reported as an effective adjunctive treatment option for bipolar disorder. Previous meta-analytic study showed that augmentation treatment with light therapy significantly decreased the severity of bipolar depression. However, most of included studies were case-control studies and several of them focused on BLT that was provided in combination with sleep deprivation therapy.

METHODS

In this meta-analysis, we used several electronic databases to search the studies and included only randomized controlled trial (RCT) studies to compare BLT with control experimental groups for treating bipolar depression with pharmacological treatment to clarify the adjunctive efficacy of BLT. We searched the databases of EMBASE, MEDLINE, Scopus, The Cochrane Central Register of Controlled Trials, the Cumulative Index to Nursing and Allied Health Literature, and Clinicaltrials.gov for studies published in English until September 19, 2019. Two researchers conducted the literature screening, data extraction, and methodological quality assessment independently. The main outcome was the response rate and remission rate. We used the Review Manager 5.3 Software for the meta-analysis.

RESULTS

Four trials with a total of 190 participants (intervention: 94, control: 96) with bipolar depression were evaluated to gauge the effects of light therapy. The meta-analysis showed risk ratios of 1.78 (95% CI 1.24-2.56, p = .002; I2  = 17%) demonstrating a significant effect of light therapy in the response rate of bipolar disorder. The meta-analysis shows risk ratios of 2.03 (95% CI 0.48-8.59, p = .34; I2  = 67%) demonstrating no significant effect of light therapy in the remission rate of patients with bipolar disorder. None of the articles reported any serious adverse effects. Manic switch rate was 1.1% in the light therapy group and 1.2% in the control group.

CONCLUSIONS

Bright light therapy is an effective treatment for reducing depression symptoms among patients with bipolar depression.

Sleep and Circadian Rhythm Disorder in Bipolar Affective Disorder

Symptoms of affective disorders encompass a range of changes to biological processes such as sleep and appetite. These processes are regulated over a 24-h cycle known as the circadian rhythm. Sleep is a particularly useful marker of this rhythm as it is readily measurable and functionally significant. Sleep disturbance is common in bipolar affective disorder and may act as a marker, and precipitant, of relapse. Circadian rhythms are modulated by environmental and social cues and have been shown to be influenced by treatment in BPAD. As such understanding of circadian rhythms may lead to a better understanding of the pathophysiology of BPAD and its treatment. This chapter will explore the neurobiology of the circadian clock and the putative role of circadian rhythm dysregulation in the pathophysiology and treatment of bipolar affective disorder (BPAD).

Light therapy with boxes or glasses to counteract effects of acute sleep deprivation

Sleep deprivation, in the context of shift work, is an increasing major public health issue. We aimed to determine whether early light administration can counteract sleep deprivation effects, and to compare LED-glasses with a traditional light therapy box. This cross-over design study included 18 individuals exposed to light therapy for 30 minutes at 5 am after one night of complete sleep deprivation, to mimic the night shift condition. Individuals were randomly exposed to 10,000 Lux light box, 2,000 Lux LED blue-enriched glasses, and control (ambient dim-light at 8 lux). Alertness, cognition and mood were assessed throughout the night and following morning. Five women and 13 men (mean 24.78 year old) presented with a progressive and increasing alteration of alertness, cognition, and mood during each sleep deprivation. A rebound was observed at 8 am resulting from the circadian drive overriding cumulative sleep homeostatic effects. Morning light significantly improved sleepiness and sustained attention from 5 to 7 am. These effects were comparable between devices and significantly different from control. Both devices were overall well and similarly tolerated. Early morning light therapy in the condition of sleep loss may have broad practical applications to improve sleepiness, sustained attention and subsequent risk of accidents.

Bright Light as a Personalized Precision Treatment of Mood Disorders

Background: The use of light for its antidepressant action dates back to the beginnings of civilization. Three decades ago, the use of bright-light therapy (BLT) for treating Seasonal Affective Disorder (SAD) was officially proposed. Since then, a growing scientific literature reports its antidepressant efficacy in both unipolar and bipolar disorders (BD), with or without seasonal patterns. This review aims to examine the management of BLT as a personalized and precision treatment in SAD, unipolar, and BD. Methods: We conducted a narrative review using Medline and Google Scholar databases up to June 2018. Results: BLT has physiological effects by resynchronizing the biological clock (circadian system), enhancing alertness, increasing sleep pressure (homeostatic system), and acting on serotonin, and other monoaminergic pathways. Effects of BLT on mood depend on several factors such as light intensity, wavelength spectrum, illumination duration, time of the day, and individual circadian rhythms. A growing body of evidence has been generated over the last decade about BLT evolving as an effective depression treatment not only to be used in SAD, but also in non-seasonal depression, with efficiency comparable to fluoxetine, and possibly more robust in patients with BD. The antidepressant action of BLT is fast (within 1-week) and safe, with the need in BD to protect against manic switch with mood stabilizers. Side effects might be nausea, diarrhea, headache, and eye irritation, and are generally mild and rare. This good safety profile may be of particular interest, especially in women during the perinatal period or for the elderly. The management of BLT needs to be clarified across mood disorders and future studies are expected to compare different dose-titration protocols, to validate its use as a maintenance treatment, and also to identify predictive biomarkers of response and tolerability. We propose clinical guidelines for BLT use in SAD, non-seasonal depression, and BD. Conclusions : BLT is an efficient antidepressant strategy in mono- or adjunct-therapy, that should be personalized according the unipolar or bipolar subtype, the presence or absence of seasonal patterns, and also regarding its efficacy and tolerability.