Using Light to Combat Depression and Sleep Better

What You Need to Know About Bright Light Therapy

March 1, 2022

Have you ever wondered if the amount of sunshine or light you get during the day influences your mood or sleep? Maybe you’re personally acquainted with the low energy and depressed mood that can come with seasonal affective disorder. Or perhaps you’ve been working so hard at your job, raising your children, or caring for elderly parents that you are spending most of your time indoors, with little to no chance to see the light of day. Whether it’s SAD or major depression, you just can’t seem to get ahead with the lifestyle interventions you’ve been trying.

If you’ve been feeling moody or sleeping poorly, it may be time to evaluate what’s going on. If you consider yourself to be a night person or have a hard time getting up in the morning, you likely have a problem with your circadian rhythm.

Light therapy provides a natural way to reset your body’s sleep wake cycle (circadian rhythm) and improve your mood without drugs or their side effects.

Lack of sunlight exposure influences brain chemistry

A plethora of factors influence your depression risk; and, not terribly surprisingly, the amount of natural light you’re exposed to has a profound effect on your body’s resilience to this disease. Our brains produce important chemicals involved with regulating mood, sleep, hunger, and other basic functions associated with how we feel. Two specific chemicals, serotonin and melatonin, are tied closely with mood and sleep. And both serotonin and melatonin are directly influenced by light exposure.  

Low light exposure risks: [i]

  • Decreased serotonin and melatonin production
  • Increased cognitive impairment
  • Reduced brain blood flow
  • Decreased alertness
  • Disrupted sleep
  • Depressed mood

Let’s look at using light to combat depression and improve circadian rhythm

The optimal bright light treatment is natural sunlight, but sunlight is not readily available at the right times in every season. Safe, specially engineered medical-grade bright light therapy devices works by affecting brain chemicals associated with sleep and mood. Bright light therapy stimulates serotonin production in the brain, causing more serotonin to be present in the body during the day. [ii] Increased serotonin production through bright light therapy improves the mood by modulating chemical mechanisms and transporter proteins, making serotonin more abundant for the brain to use.

Bright light therapy has been found to: [iii]

  • Improve blood serotonin levels
  • Improve happiness
  • Improve depression scores
  • Decrease the stress hormone cortisol
  • Prepare the body for sleep

Serotonin is converted to melatonin in the presence of darkness. Hence, it’s important to reduce light exposure closer to bedtime to reap the maximum benefit of bright light therapy.   

Light therapy devices filter out UV rays and most studies are conducted using 10,000 lux white or blue light. [iv] These light therapy devices emit a bright blue or white light that mimics the brightness of natural outdoor light. Using a medical grade light therapy device has been shown to be an effective, front-line treatment for seasonal affective disorder (SAD) as well as other forms of depression and sleep disorders.

When you might want to try bright light therapy:

  • If your healthcare provider recommends it to treat SAD or depression
  • When you have trouble sleeping and want to try a treatment with no side effects
  • To reduce jetlag
  • If you are a shift worker
  • If you have depression symptoms and want to work with your doctor on lowering your medication dosage

How to use a bright light therapy device

To use light therapy, you’ll sit near an electronic device called a light therapy box or use light therapy glasses. Use your light therapy device for 30-60 minutes every morning within 10 minutes of awakening (at the time you want to wake up). Dr. Nedley recommends that it is best to use your light therapy by 7 AM.

Light therapy for insomnia

Use your light box or glasses consistently for 30 minutes at the same time each day. You’ll notice that your body is getting tired earlier in the evening. It can take up to 10 days or more, but with time you’ll fall asleep earlier and faster.  

Light therapy for early morning awakenings

If you consistently wake up at 2:00 AM, 4:15 AM, etc. every night and struggle to fall back sleep, you’re likely experiencing early morning awakenings. Dr. Nedley recommends 20 minutes of light therapy exposure 12 hours opposite the time you’re awakening. This could be light therapy or going outside in the bright natural sunlight. For example, if you’re waking up at 2:30 AM, get 20 minutes of light exposure at 2:30 PM.

In addition, implement good sleep hygiene practices, such as mentioned here. If you are experiencing persistent sleep disturbances, consult your doctor to evaluate you for other medical conditions, like sleep apnea.

Light therapy for jet lag

Changing time is a common cause of sleep disturbances. Light therapy can help prepare your body for a circadian rhythm change and thus reduce jet lag symptoms. For three or four days before traveling, adjust the timing of your bright light therapy from your current time zone to doing it at your upcoming time zone. Only use your light device once each day as you prepare for the new time zone.  

For example, if I am traveling from California to Florida, I want to use my light box at the new time I want to wake up at in Florida. Instead of using my light box at 6 AM Pacific Time, I am going wake up at 3 AM Pacific Time (which is 6 AM Eastern Time) and use my light for 30 minutes. After 30 minutes (with my eyes open!), I go back to sleep and do not use the light again that morning. When I get to Florida, I’ll continue my light treatment at the new time zone, at the time I want to wake up there – 6 AM Eastern Time. In summary, all you need to do is calculate the time difference and use your light box at the new wake up time in your present time zone for several days before traveling.

Light therapy for shift work

Recent evidence on shift work suggests that “early morning light therapy in the condition of sleep loss may have broad practical applications to improve sleepiness, sustained attention and subsequent risk of accidents.” [v]  

Does light therapy have any side effects?

Light therapy is a safe treatment for SAD, depression, mood disorders, and sleep disturbances. Light therapy research shows that blue light therapy with lower intensity lux is just as effective as 10,000 lux white light therapy and does not have the increased risk of macular degeneration and cataracts. [vi]

Some individuals experience short-lived, mild side effects such as eye strain or headache from light therapy use. However, they generally go away within a few days of beginning light therapy. [iv] To reduce possible discomfort, do not look directly at the light source and keep other lights on at the same time.

How long does it take for bright light therapy to work for depression?

Some individuals experience improvements with as little as 20 minutes at their first treatment, but light exposure for 40 to 60 minutes results in even greater improvement. [vii] Generally, light therapy can begin improving symptoms in as little as a few days, but in some cases, it can take two or more weeks for effects to be noticeable.     

Remember, light therapy is one of many synergistic behavioral and cognitive tools. As with any new medication, give your body time to adjust as you implement a new regime.  

Get the most out of your light therapy

Get the right light therapy device

A medical grade light therapy box has these two basic specifications: blue or white wavelength (color) and 10,000 lux or 10,000 lux equivalents. There are lots of light devices out there of all different sizes, light intensities, and colors, so do your research when making your selection. We recommend AYO glasses because of their engineering and convenience.

Use your device consistently

Use your light therapy device every day for 30-60 minutes within 10 minutes of awakening (at the time you want to wake up). For example, if you want to wake up at 6 AM, you need bright light exposure by 6:10 AM for 30-60 minutes. For adults, Dr. Nedley recommends going to bed about 9 PM and waking up around 5:30 or 6 AM.  

Many individuals consistently use light therapy from fall through spring when there is the least amount of sunlight. Pay attention to your mood and sleep patterns. We recommend making light therapy a daily habit to see the most significant benefits. Carefully evaluate your mood, sleep, and other symptoms to see if you notice an effect from not using your light every day. You may need to restructure your schedule to prioritize this simple treatment. But if you do get out of the habit of using your light therapy, it’s easy to pick back up. Whether using a light therapy device or going outside for sunshine, it’s time to see yourself in a new light as you give your brain what it needs for optimal mental health.



[i] Kent, S., McClure, L., et al (2009). Effect of sunlight exposure on cognitive function among depressed and non-depressed participants: a REGARDS cross-sectional study. Environmental health: a global access science source, 8, 34.

[ii] Oldham, M., & Ciraulo, D. (2014). Bright light therapy for depression: a review of its effects on chronobiology and the autonomic nervous system. Chronobiology international, 31(3), 305–319.

[iii] Lieverse, R., Van Someren, E., et al (2011). Bright light treatment in elderly patients with nonseasonal major depressive disorder: a randomized placebo-controlled trial. Archives of general psychiatry, 68(1), 61–70.

[iv] Maruani, J., & Geoffroy, P. (2019). Bright Light as a Personalized Precision Treatment of Mood Disorders. Frontiers in psychiatry, 10, 85.

[v] Comtet, H., Geoffroy, P., et al (2019). Light therapy with boxes or glasses to counteract effects of acute sleep deprivation. Scientific reports, 9(1), 18073.

[vi] Meesters, Y., Winthorst, W., et al (2016). The effects of low-intensity narrow-band blue-light treatment compared to bright white-light treatment in sub-syndromal seasonal affective disorder. BMC psychiatry, 16, 27.

[vii] Virk, G., Reeves, G., et al (2009). Short exposure to light treatment improves depression scores in patients with seasonal affective disorder: A brief report. International journal on disability and human development: IJDHD, 8(3), 283–286.

About the author

Cami Martin Gotshall, MPH, is the Health Education Director for Nedley Health. Her passion is disseminating information on living a mentally healthy lifestyle to people around the world. Cami works closely with all Nedley Health programs to continually enhance and expand each program. She lives in Idaho with her husband Tim.