Bright Light Therapy for Insomnia

Bright light therapy for sleep problems?

It doesn’t sound logical: how can bright light help you sleep? Doesn’t light keep you awake?

Well yes, light does keep you awake. That is precisely why light is a useful tool to help correct certain sleep problems in which the sufferer’s night-day cycle is out of sync with the rest of the world. The most common sleep problem of this type is Delayed Sleep Phase Disorder.

What is Delayed Sleep Phase Disorder?

Delayed Sleep Phase Disorder (DSPD) is a problem with the body’s internal clock, or circadian rhythm. This is the cycling of our sleep and metabolic functions that normally fluctuates in sync with night and day. For example, for most people, body temperature decreases at night and increases during the day. We tend to get sleepy around 10 p.m., and wake up around 6 a.m. (I said “tend to”!)


But for some people, the day seems to run on a totally different clock. For people with DSPD, the day is shifted 3-6 hours later. They do not become sleepy until 1 a.m. and do not want to wake up until 10 a.m. It’s a problem if they need to wake up at 6 a.m. to go to school or to work. So they tend to feel tired and sluggish throughout the day. Then night comes but they can’t fall asleep! For all appearances, the person with DSPD is suffering from insomnia, or some other sleep problem.

DSPD generally starts in adolescence or young adulthood. According to the International Classification of Sleep Disorders, DSPD occurs in 7-16 percent of young people. About 10 percent of my teen sleep coaching clients who complain of insomnia actually have DSPD. These teenagers often describe themselves as “night owls”.

Paying attention only to panel B of this figure, notice that the sleep time for a person with DSPD is four hours later than normal.

Bright light therapy works like this. For the patient with DSPD in this figure, they sit in front of a bright light box starting at around noon. They stay there for 1-2 hours. They repeat this pattern for 2 days. Then the hour that they sit in front of the box is advanced (moved earlier) by an hour for another two days.

Bright light therapy re-sets the internal body clock earlier and earlier until the patient is waking up at the “normal time”, say 6 a.m.

Bright Light Therapy TOO Bright?

These light boxes are very intense. Some people complain that the lights are too bright and they quit the therapy because the experience is too unpleasant.

It turns out that when bright light therapy is combined with other therapies such as cognitive behavior therapy, a less intense light box may be adequate to treat the problem.

The color of the light also turns out to be important. Light at the blue-green end of the spectrum is more effective at achieving the desired result. This type of light may not feel as harsh as intense white light.bright light therapy 3

Light during the day, dark at night

Light therapy alone will not treat DSPD. The patient may also need to break some bad habits. For example, electronic devices with screens need to be turned off in the evening, ideally two hours or more before bed. This change in behavior may be easier said than done for some young people. The problem is that exposure to the blue-spectrum light at night can undo the effects of the light training in the morning.

Cup of Joe? No.

People with DSPD also need to be careful about caffeine consumption. Coffee and other caffeinated beverages should be avoided during the four hours prior to bed time. Energy-dense foods, especially ones high in sugar, are stimulating and should be avoided in the evening. This may pose a problem for teenagers who are fond of dessert.

What about exercise?

It’s absolutely essential for health, but not in the evening! Especially with intense exercise, people find it much more difficult to “wind down” when they’ve exercised too close to bedtime. I recommend adjusting the schedule to get exercise done in the morning.bright light therapy 2

Treat other conditions

Many teenagers also suffer from anxiety and depression. The relationship between sleep problems and psychic distress are complex. It’s difficult to know sometimes which came first, the sleep problem or the distress. One thing is for certain: sleep problems make psychic distress worse and vice versa! I recommend getting help for anxiety and depression if possible. As I mentioned before, cognitive behavioral therapy combined with light therapy is effective. If the patient has the time and the motivation, talking therapy can help solve both sleep and mood problems.


  • Bright light therapy is an effective treatment for Delayed Sleep Phase Disorder
  • Avoid screen time at night!
  • Exercise regularly, but do it early in the day
  • Avoid caffeine and energy-dense foods at night
  • Pay attention to anxiety and mood problems



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Rob Lindeman

Rob Lindeman is a sleep coach, entrepreneur, and writer living in Massachusetts. Ready to Get Rid of the Pacifier? Sign up for our FREE Video eCourse: The Paci-Free Method

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