Light, Sleep and Mental Health
Light, both natural and artificial, can affect our health and mental health in several different ways. Depending on the time of day, light exposure can promote or disrupt sleep. A persistently disrupted sleep cycle can contribute to a variety of health problems, including heart disease, obesity and mental health disorders. Research is also beginning to clarify non-circadian effects of light – light can have a direct impact on the sleep and mood centers in the brain.
Helen Burgess, Ph.D., with the University of Michigan, presented a video talk on the health impacts of light this summer as part of series on novel research from the National Institutes of Health Center for Complementary and Integrative Health. Burgess describes three areas that regulate our lives – our internal circadian clock; our exposure to external light/dark; and our social clock, the schedule determined by work and other responsibilities and activities. Light enters the eyes, even through closed eyelids during sleep, sending a signal in the back of the retina and to the circadian clock in the brain.
Light, Sleep and Our Brains
Burgess notes that most of us need morning light to stay in sync with 24-hour day. One exception may be older adults—as we age, we tend to go to sleep and wake up earlier. But for most, too much light at night can be problematic. Surveys show that many of us use light-emitting devices before going to sleep. This light can reduce the natural production of melatonin and contribute to a shift in our natural sleep cycles. While evening light of any kind can suppress production of melatonin, blue light (which emanates from smartphones and other sources) at night is stronger. Recent research has also found that people vary a great deal in their sensitivity to light. Evening light that significantly impacts one person may have very little effect on another.
Light’s Usage for Better Mental Health
In the work environment, whether in an office or at home, Dr. Pragya Agarwal, ADD AFFILEA suggests that "sufficient and suitable lighting usually needs a combination of natural and artificial lighting.” In particular, the artificial lighting should be able to adjust for different activities or functions or for individual needs. “There is sufficient evidence now to show that well-being in the workplace can be hugely improved by providing lighting that mimics natural daylight, by bringing more natural light in with large windows, by providing suitable levels of illumination for visual acuity, and by providing personalized lighting that can be adjusted,” Agarwal recently wrote in Forbes.
The positive effects of light have been increasingly being explored as treatment. Morning bright light therapy has for some time been used to treat seasonal affective disorder and has recently has also showed promise in treating non-seasonal depression and other conditions. A recent meta-analysis looking at nine studies concluded that bright light therapy administered for two to five weeks was an effective depression treatment. In fact, bright light treatment is proving to be an effective antidepressant for some without the side effects of many medications, according to Dr. Burgess. Some new research is showing possible benefits of light therapy for fibromyalgia pain, chronic lower back pain and posttraumatic stress disorder.
Based on the recent research, Dr. Burgess offers a few light-related wellness tips:
- Maintain a regular sleep schedule:
- keep a consistent sleep and wake time
- try to get 7 to 8 hours of sleep a day (also the recommendation from the American Academy of Sleep Medicine)
- Get light exposure during the day:
- outside or near a window with direct light
- morning light is especially good
- at least 30 minutes to an hour
- Minimize artificial light after sunset:
- dim/less light especially from electronic devices
- not close to the eyes (TV is better than smartphone/tablet)
- not in the hour before going to bed
- National Center for Complementary and Integrative Health. Integrative Medicine Research Lecture Series, Video:; Lighting Up Our Lives: How Light Influences Our Mental and Physical Health. Aired Tuesday, June 30, 2020.
- Al-Karawi, D, Jubair, L. Bright light therapy for nonseasonal depression: Meta-analysis of clinical trials. J Affect Disord. 2016 Jul 1;198:64-71.
- Agarwal, P. How Does Lighting Affect Mental Health In The Workplace. Forbes. Dec. 31, 2018.
- Blue light has a dark side: What is blue light? The effect blue light has on your sleep and more. Harvard Health Letter, updated July 7, 2020.