Effect of Blue Light Exposure on Mood (BLM)

Mood dysregulation and suicidal ideation are closely associated with disruption of sleep and circadian rhythms. Moreover, sleep problems and circadian disruption are commonplace features of military life. Critically, specifically timed light exposure plays a powerful role in regulating mood, circadian rhythms, and sleep-wake patterns. Therefore, we propose to conduct a large-scale clinical trial on the effectiveness of morning light exposure treatment for improving sleep-wake patterns, emotional and mental health, and suicidal thoughts in military personnel.

The objective is to determine the effectiveness of daily morning blue light therapy (BLT) for regulating the circadian rhythm to improve mood and reduce suicidal thinking. Our working hypotheses are that daily exposure to morning blue light for two weeks will 1) lead to a phase advance entrainment of sleep timing relative to a placebo light therapy, 2) lead to improved/sustained mental health outcomes, including suicidal ideation, relative to a placebo light therapy, and that 3) most military Service members will rate the use of a light "headset" device acceptable as a treatment option after their experience. Over a 3-year period of performance, we aim to 1) determine the effectiveness of daily morning BLT for regulating circadian timing and sleep, 2) determine the effectiveness of daily morning BLT for sustaining or improving mental health outcomes, including suicidal ideation, relative to placebo light therapy, and 3) determine the acceptability and "buy-in" from military personnel using a daily light headset device. During this study, 400 military personnel will complete a double-blind, placebo-controlled, counterbalanced, crossover design study of the effects of 30-minutes of daily morning blue light therapy (BLT) versus amber placebo light therapy (PLT) on measured sleep and mental health outcomes. Participants will complete two weeks of morning BLT with a commercially available headset with four built-in light-emitting diode (LEDs) and internal compliance monitors, and two weeks wearing the same type of glasses fit with amber placebo light-emitting diode (LEDs), in a counterbalanced order, separated by a four-week washout period. An online assessment battery for mental health and suicidal ideation will be completed before and after each treatment period, and sleep/circadian rhythms will be monitored throughout via 5-channel at-home EEG recordings, continuous actigraphy and daily brief sleep/mood/suicidal ideation logs.

All recruitment, data collection, and testing will occur online, through remote interactions. Via a web-based portal, participants will complete a baseline assessment battery to document their sleep habits, mental health, and suicidal ideation. After the baseline assessment, participants will be randomly assigned to one of two treatment orders: Order A) BLT for 2 weeks, a 4-week washout period, and 2 weeks of PLT, or Order B) PLT for 2 weeks, a 4-week washout period, and 2 weeks of BLT.

Participants will not have any knowledge of which of the two condition groups they are apart of during or after the study. The investigator will not have any knowledge of which of the two condition groups the participant is apart of during or after the study. Condition groups will be randomly assigned via the web-based portal used for recruitment, data collection, and testing.

Blue light treatment for 2 weeks, a 4-week washout period, and 2 weeks of placebo (amber) light treatment.

Blue light at the wave length of 470nm will be emitted for 30 minutes over a 2 week time frame, from commercially available ayo glasses, as a method to regulated circadian rhythm.

Amber light at the wave length of 578nm will be emitted for 30 minutes over a 2 week time frame, from commercially available ayo glasses, as a control to investigate the regulation of circadian rhythm.

The mean response on the Beck Depression Inventory (BDI), which measures key symptoms of clinical depression. Higher scores on this measure indicate the presence of more severe depressive symptoms.

Participants will be assessed the day before the initiation of the first two-week intervention period and the day following the conclusion of the first two-week intervention period. This will be repeated for the second two-week intervention period.

The mean response on the Death Implicit Association Test (D-IAT), which measures the strength of an individuals implicit association between themselves and death. Positive scores: support a stronger association between 'Me-Death' and 'Not Me-Life' than for the opposite pairings; Negative scores: support a stronger association between 'Me-Life' and 'Not Me-Death' than for the opposite pairings. Scores closer to 1/-1 indicate a stronger association than those near 0.

Participants will be assessed the day before the initiation of the first two-week intervention period and the day following the conclusion of the first two-week intervention period. This will be repeated for the second two-week intervention period.

The mean response on the Beck Hopelessness Scale (BHS), which measures hopelessness with a series of optimistic or pessimistic statements regarding thoughts about the future, motivation, and expectations. Higher scores on this scale indicate more severe hopelessness.

Participants will be assessed the day before the initiation of the first two-week intervention period and the day following the conclusion of the first two-week intervention period. This will be repeated for the second two-week intervention period.

The mean response on the Suicidal Cognitions Revised (SCS-R), which predicts future suicidal attempts in patients who deny suicidal ideation and prior suicide attempts. Higher scores on this scale are associated with a greater likelihood of an individual attempting suicide in the future.

Participants will be assessed the day before the initiation of the first two-week intervention period and the day following the conclusion of the first two-week intervention period. This will be repeated for the second two-week intervention period.

The mean response on the University of California Los Angeles Loneliness Scale (UCLALS), which measures an individuals subjective feelings of loneliness and social isolation. Higher scores indicate a greater feeling of loneliness.

Participants will be assessed the day before the initiation of the first two-week intervention period and the day following the conclusion of the first two-week intervention period. This will be repeated for the second two-week intervention period.

The mean response on the Interpersonal Needs Questionnaire (INQ),which measures individual sense of perceived burdensomeness (PB) and thwarted belongingness (TB). Higher scores on these sub-scales indicate a greater desire for death/suicide.

Participants will be assessed the day before the initiation of the first two-week intervention period and the day following the conclusion of the first two-week intervention period. This will be repeated for the second two-week intervention period.

The mean response on the Connor-Davidson Resilience Scale (CD-RISC), which measures an individuals adaptability and ability to thrive in adversity. Higher scores on this scale indicated higher resilience which is inversely associated with suicidal ideation.

Participants will be assessed the day before the initiation of the first two-week intervention period and the day following the conclusion of the first two-week intervention period. This will be repeated for the second two-week intervention period.

Inclusion Criteria: Ages 18-60 years English as primary language At least an 8th grade reading level Score ≥ 5 (i.e., mild depression or greater) on the Patient Health Questionnaire 9 (PHQ-9) Exclusion Criteria: Score in non-depressed range on Patient Health Questionnaire 9 (PHQ-9) (< 5) History of psychotic disorder or manic episodes Current or prior history of eye disease History of migraine headaches Current or prior history of sleep-related breathing disorders Self-reported use of sedative hypnotic sleep medications or melatonin supplements Self-reported use of prescription stimulants Self-reported excessive use of caffeine (i.e., > 500 mg per day) Plans to engage in nightshift work during the 8-week course of the study

There is no plan to make individual participant data available to other researchers. All data that will be shared from this clinical trial will be shared in summary data sets.

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