New study with Chromaviso Circadian Lighting shows significant long-term effect on depression and improved sleep after only 3 weeks
A new Danish clinical study shows for the first time that Chromaviso’s circadian lighting not only helps patients with depression in the short term but also has a significant long-term effect on patients with severe depression.
The study, published in the scientific journal Chronobiology International (August 2025), was conducted by Chief Physician, MD, Clinical Research Associate Professor Klaus Martiny, and Architect, PhD Carlo Volf from the University of Copenhagen and DTU, in collaboration with Chromaviso and the Capital Region of Denmark.
The researchers investigated the effect of dynamic circadian lighting with Chromaviso's circadian protocol in patients with severe depression in a psychiatric ward.
The light automatically follows the human biological circadian rhythm and changes color and intensity during morning, day, evening and night. The light sequence is inspired by daylight on a May day. In the morning, the light rises gently like a sunrise and gives a warm amber light like a sunrise. In the middle of the day, it changes to a bright white light, reminiscent of the sun at its highest point in the sky outside. In the afternoon and evening, the light gradually dims and becomes warmer again, gradually dimming like at sunset. At night, the light is blue-free and warmly dimmed, so patients and residents know it's night, but staff can still work and recover in it.
Clear results - both short and long term
The trial involved 60 patients hospitalized with severe depression. They were randomly assigned to rooms with either dynamic circadian lighting or traditional, static LED lighting.
After three weeks of treatment, the results were striking:
The patients who stayed in circadian lighting slept about an hour longer and woke up fewer times during the night. An effect that is of great importance for both recovery and mental stability.
Female patients in particular experienced a faster improvement in mood and symptoms.
"The results show a short-term antidepressant effect in females and a sleep-promoting effect for the whole group and a long-term antidepressant effect for the whole group," the researchers write in the article.
At the six-month follow-up, the patients in circadian light continued to show significantly lower levels of depression than the control group. This is the first time such a long-term effect of circadian light has been documented in a controlled clinical study.
Sleep - the key to stability and recovery
Sleep plays a central role in both depression and treatment. Disrupted circadian rhythms and restless sleep are common among patients with depression. The dynamic light helped patients fall asleep faster, sleep longer and wake up more rested.
By mimicking natural daylight, the circadian light sends clear signals to the brain about when it's day and night - helping the body regain its rhythm.
Patients experienced the light as safe and comfortable
In addition to the clinical improvements, patients found the circadian lighting to be more natural and pleasant to be in.
"The dynamic lighting condition was found more satisfactory and comforting than the static light," the researchers write.
The blue-free night light also contributed to calm and security in the evening and night hours without disturbing the circadian rhythm.
Read the full research article here