Light therapy glasses for depression in teenagers

This article is part of the 2018 NMJ Oncology Special Issue. Download the full issue.

Relation

Kirschbaum-Lesch I, Gest S, Legenbauer T, Holtmann M. Feasibility and effectiveness of light therapy for depressed adolescents in the inpatient setting. (Link removed). 2018;46(5):423-429.

Draft

Open-label, single-arm, prospective clinical trial

Goals

To evaluate prolonged use (4 weeks) of blue light therapy (BLT) glasses on multiple depression measures in adolescent inpatients and to compare BLT glasses results with a previous study at the same institution that used a bright light therapy box for 2 weeks in a similar population.

Participant

Thirty-nine teenagers (32 females, 7 males, ages 12–18 years) hospitalized with moderate to severe depression for at least 4 weeks were included. Depression was defined by the Beck Depression Inventory II (BDI-II), a 21-item self-assessment questionnaire of depressed mood in the past 2 weeks. 32 participants reported “severe depressive symptoms” according to the BDI-II score.

In addition to treatment as usual (TAU), light therapy was administered. This treatment was not specified, but 36% of participants received pharmacological therapy with antidepressants.

Exclusion criteria included a diagnosis of schizophrenia; symptoms of psychosis or suicidality; treatment with antipsychotics or beta-blockers; Pregnancy; hypersensitivity to light; and eye diseases.

The comparison group from a previous study (n=39) at the same institution that used blue light box therapy had no significant differences in age, gender, antidepressant use, or BDI-II scores at baseline.

intervention

Participants received BLT via bright glasses (brand name Luminette) for 30 minutes in the morning every weekday for 4 weeks. The glasses delivered 10,000 lux of blue light aimed at the bottom of the eyes, allowing participants to go about their normal morning activities.

Study parameters assessed

Participants were assessed at baseline (T1), 2 weeks after baseline (T2), at the end of the 4-week intervention (T3), and 2 weeks after trial completion (T4) for the following objective and subjective measures:

• Depression, ermittelt nach BDI-II
• Schlaf, bewertet durch den Schlaffragebogen B überarbeitet (SF-BR), ein 31-Punkte-Fragebogen zur Bestimmung der Qualität und des erholsamen Charakters des Schlafes
• Chronotyp, bestimmt durch den Morningness-Eveningness Questionnaire (D-MEQ), einen 15-Punkte-Fragebogen, der die zirkadiane Präferenz und Phasenverschiebung bewertet
• Globaler Schweregrad der Symptome und Gesamtveränderung während der Studie, bestimmt durch die Clinical Global Impressions (CGI)-Skala, ausgefüllt vom Therapeuten.

The previous study used a light box that provided 10,000 lux of white light. This intensity is comparable to sunlight 40 minutes after sunrise.

Primary outcome measures

Effectiveness of blue light therapy glasses on the subjective and objective measures listed above; Comparison with historical data from a 2-week study at the same institution using a light box with equivalent lux.

Key insights

BDI-II scores improved from start to end of the study (T1 to T4), with statistically significant change between T1 and T2. Clinical Global Impressions results were significantly improved between T2-T4 and T3-T4. Sleep improved from baseline (T1) to week 4 (T3). The chronotype has not changed significantly.

The hypothesis that a longer BLT duration (4 weeks) might have better effects than a 2-week duration was refuted in this study. Depression and sleep were not different at 4 weeks (T3) when using BLT glasses for 4 weeks compared to BLT boxes for 2 weeks.

Practice implications

It is well known that BLT can be useful for treating seasonal and non-seasonal depression.^1-3Light boxes are becoming increasingly popular, especially in places with little light during the winter months. This study specifically compares the effectiveness of a new type of treatment device, lightweight “glasses,” with the more widely used light boxes. The lightweight glasses are worn like regular glasses, but have a type of visor that extends about an inch from the face and shines a light onto the eyes. The disadvantage of a light box is that the user must remain stationary and is asked to look directly into the light box a few times during the treatment. The light glasses emit light that covers the lower half of the eye without having to look directly into the light. This allows a person to go about their normal morning routine while using it, which could potentially increase compliance.

This study is interesting because it provides a simple tool to help depressed teenagers improve mood with a very low-impact intervention. Another fascinating finding is that the effectiveness of the BLT glasses peaked after 2 weeks. Extension of treatment to 4 weeks showed no further improvement, so it appears that BLT treatments rapidly affect the underlying pathophysiology and this change has a sustained quality.

The light glasses emit light that covers the lower half of the eye without having to look directly into the light. This allows a person to go about their normal morning routine while using it, which could potentially increase compliance.

Would exposure to natural sunlight have similar effects? Several studies examined reported sun exposure and found it to be inversely correlated with depressive symptoms, but a PubMed search found no studies directly comparing sunlight with bright light therapy.^4-6Perhaps in the context of an inpatient setting, from a study design perspective, a light box or light glasses are easier to control than outdoor exposure. However, it would be useful to know whether BLT as glasses or boxes has unique antidepressant effects, rather than sending the affected teenager outside without shade for 30 minutes every day.

An interesting difference between light boxes and glasses is the type of light emitted. Light boxes use white light, and the jars use only blue light. Both emit the same light intensity of 10,000 lux, which is approximately the intensity of sunlight 40 minutes after sunrise. However, wavelengths from the blue part of the visible spectrum are the strongest regulator of circadian rhythms and more closely approximate the stimulation felt by sunlight.⁷Blue light reduces the release of melatonin, which can increase alertness. Conversely, blue light blocking glasses worn 3 hours before bedtime will significantly reduce the time it takes to fall asleep and improve overall sleep rest.⁸

Exposing the body to natural light and dark cycles makes sense to regulate and improve sleep quality, but how does this affect mood? Does sleep disorder cause depression, does depression cause sleep disorder, or are they concurrent features of the same process? The participants in this study all took a morning-evening questionnaire and none of them were classified as strong morning people. Evening mood is generally associated with depression, especially in teenagers.^9-12So we see that disrupted circadian rhythms and sleep-wake cycles are linked to depression, but what happens physiologically to light that helps improve mood?

From a biochemical perspective, several neurotransmitters respond to light and dark cycles. Melatonin, serotonin, dopamine, and norepinephrine all respond to BLT. Melatonin, dopamine and serotonin are all produced in the retina. Retinal dopamine production is stimulated by BLT; Conversely, dopamine deficiency is associated with symptoms of depression.^13-14Blue light therapy also suppresses the production of retinal melatonin, and blue light blocking glasses stimulate melatonin production. Under normal circumstances, melatonin is highest at night and during sleep. People with sleep disorders and depression have a disruption in normal circadian plasma melatonin levels.^15-16

Tryptophan, serotonin, and catecholamines such as dopamine and norepinephrine are also involved in the relationship between light exposure and depression symptoms. Several studies have used tryptophan depletion to induce relapse of depressive symptoms in patients in BLT-induced stable remission.^17-19Tryptophan depletion is achieved by giving patients a tryptophan-free amino acid mixture, limiting the substrate needed for production to 5-HTP (hydroxytryptophan) and subsequent serotonin production. Serotonin secretion is then reduced even when treated with bright light, causing the resurgence of depressive symptoms.²⁰Similar studies show the return of depressive symptoms with catecholamine deficiency.

This study illuminates the fascinating interplay between light and dark cycles and our internal circadian rhythm. Being awake and exposed to morning sunlight initiates the release of neurotransmitters that improve energy and mood during the day. Conversely, dim light and darkness promote melatonin to calm the brain and induce restful sleep. By using a simple, low-impact intervention to mimic morning sunlight, we can help patients improve their mood and sleep.