There is a need to develop new treatments for depression as the current options are lacking in efficacy, are associated with severe side effects, and are costly to implement and use. This is the case for antidepressants, psychotherapy, and the developing area of neurostimulation methods that often require daily treatments at a hospital or costly devices (e.g., rTMS, T-PEMF, vagal stimulation).

From the basic chronobiological field, several treatments have emerged for seasonal and non-seasonal depression and bipolar disorder since the 1980th: light therapy, wake therapy, sleep phase advance, and more recently, dark therapy.

Now, an additional treatment has been developed, tested, and found to be effective — Circadian Reinforcement Therapy (CRT).  This method is considered a twin to the Interpersonal and Social Rhythms Therapy developed by Ellen Frank and coworkers. CRT is specialized psychoeducation focusing on increasing the strength of the most critical zeitgebers: light (electrical and daylight), social contact, exercise, and meals, but does not use formalized psychotherapy. Instead, a psychoeducational framework facilitates changes in daily habits regarding opportunities to strengthen and temporally structure zeitgebers during the 24-hour day. CRT was developed based on observations of patients from a psychiatric hospital with severe depression. In the weeks after discharge, it was found that these patients drifted to a later sleep schedule and that this drift was associated with a deterioration of their mood.  In CRT, patients are educated and encouraged to achieve exposure to more zeitgeber input at the right time. The timing of zeitgeber exposure is essential, especially regarding light, where light at the right time and darkness at the right time are crucial.

A  randomized controlled trial with 103 in-patients with severe depression were followed for four weeks after discharge. In this study, an electronic system (Monsenso) was used to facilitate the implementation of the CRT elements. Patients were monitored daily on their mood, sleep, and activity (via a Fitbit bracelet), and graphical data representations were automatically created for both patients and investigators. This enabled early detection of changes in mood and sleep and facilitated timely advice to adjust late sleep or low activity. Predetermined trigger points in the self-assessed data elicited phone calls to patients. Blind depression levels were assessed using the Hamilton Depression Rating Scale.

Results showed that the CRT group, compared to a treatment-as-usual (TAU) group, had a significantly larger reduction in depression scores and that this effect was higher if the intervention was started at or immediately after discharge. Self-assessed evening mood and sleep quality were significantly better in the CRT group, and this group also exhibited an earlier sleep onset and longer sleep duration. The day-to-day variability of self-assessed mood, sleep, and sleep quality was significantly lower in the CRT group, indicating better functioning circadian regulation.

This research shows that straightforward, ordinary elements in daily life can improve the treatment of depression. A greater clinical focus on the circadian system, as it shows itself in sleep and mood regulation, should be implemented using the CRT method in clinical practice.

Klaus Martiny


Professor of Clinical Psychiatry, Department of Clinical Medicine, University of Copenhagen

Senior Consultant at Psychiatric Centre Copenhagen

Head of New Interventions in Depression (NID-Group)