Interim analysis of preliminary results indicated a need for protocol re-design.

The aim of this study is to improve the treatment effect for outpatients with depression by adding regular daily morning daylight exposure to their treatment with antidepressants. Patients will wear a personal light tracker to keep them motivated. Our hypothesis is that patients daily exposed to morning daylight, as a supplement to standard treatment for depression, will achieve significantly higher antidepressant effect that patients receiving standard treatment alone. Furthermore, we hypothesize that they will experience improved well-being and sleep.

Due to inadequate efficiency of existing medical and psychotherapeutic treatments for depression there is a need for investigating the efficacy of adjunctive treatments. Light therapy has proven efficient as an add-on treatment for depression, but some patients might prefer being outdoors rather than sitting in front of a light therapy screen. However, no high-quality studies, have so far investigated the antidepressant and other potential positive effects of regular exposure to morning daylight for patients with unipolar depression.

The aim of this study is to examine the efficacy of morning daylight as add-on to treatment as usual in patients with depression. Efficacy is measured as reduction of depressive symptoms, improvement of sleep quality, and improvement of well-being.

Methods and material: A randomized controlled trial comprising 150 patients diagnosed with unipolar depression aged 18-50 years will be conducted. Patients are included after giving informed consent and the study period is 6 weeks. A wearable Personal Light Tracker, measuring the amount off light received, will be provided for all participants. Participants will be randomized into the following groups:

Group 1: Daylight (outdoor daylight exposed stay for minimum 30 minutes per day before 1 pm). To motivate patients to go outside they will receive psychoeducation on the connection between exposure to morning daylight and a possible antidepressant effect, and they are introduced to potential options for outdoor activities. A detailed instruction to the personal light tracker and the matching app, for monitoring the amount of light received throughout the day, is provided.

Group 2: Control group receiving treatment as usual. Patients will wear a personal light tracker but they are not introduced to the light-monitoring-app.

Inclusion Criteria:

• Fulfilling criteria for an ICD-10 diagnosis of unipolar depression (F. 32.0, F.32.1, F.32.2, F32.3, F. 32.8. F.33.0, F.33.1, F.33.2, F. 33.3)
• Hamilton Depression Score (HAM-D17) ≥ 12
• In treatment with the same antidepressant medication 14 days prior to inclusion
• The participant must have access to a smart phone

Exclusion Criteria:

• Actual treatment with Electro Convulsive Therapy (ECT)
• Seasonal Affective Disorder (SAD)
• Known sleep disturbances (sleep-apnoea, narcolepsy, or "restless legs syndrome")
• On lithium, agomelatine, melatonin and/or mirtazapine
• Known eye disorders
• Current alcohol- or drug abuse
• Current user of Light therapy