Study Reveals Why Even a Little Light Can Disrupt Your Sleep Patterns

Table of ContentsView AllTable of ContentsHow Light Affects SleepSide EffectsQuantity and QualityReduce Light ExposureLights OnFear of the DarkOther Sleep Disruptors

Table of ContentsView All

View All

Table of Contents

How Light Affects Sleep

Side Effects

Quantity and Quality

Reduce Light Exposure

Lights On

Fear of the Dark

Other Sleep Disruptors

Researchers from a 2016 study looked at the impact of light pollution—light from billboards, streetlights, buildings, cars, and more—on sleep quality. They found that even a little light—such as that from outdoor nighttime lights—candisrupt sleepand increase the risk of disease.

Exposure to excessive outdoor lights at night (light pollution) made it more likely for the study participants to wake up confused, feel fatigued andexcessively sleepy, and experience impaired functioning during the day.However, the impacts of light on your sleep are not limited to light pollution alone.

How Keeping the Lights on Affects Sleep

Sleeping with the lights on can negatively affect your sleep quality and make it harder to fall asleep at night (and, in turn, more challenging to wake up in the morning).

Your brain produces the hormonemelatonin(the “sleep hormone”), which leads to drowsiness and sleep. Lights prevent the production of melatonin, making it harder to fall asleep.Additionally, light shortens the time that your brain releases melatonin, affecting sleep quality.

Light exposure before bedtime and during the night increases the time it takes to fall asleep, which can disrupt the internal body clock (circadian rhythm), making it harder to maintain a sleep schedule and get quality sleep.When the cycle continues, it leads to further decreased quality of sleep and an irregular sleep schedule.

Side Effects of Sleeping With the Lights On

1. Depression

Nighttime light exposure has been found to increase the risk of depression symptoms andclinical depression.Light exposure prevents you from getting enough quality sleep, and depression risks and symptoms increase with sleep challenges.

Nighttime light exposure also interferes with melatonin production and can disrupt your circadian rhythm, which can also contribute to depression.

2. Obesity

Being exposed to artificial light at night is linked toobesity. One study found that women who sleep with light are 17% more likely to gain weight than women who do not.The weight gain noted in this study is partially due to habits such as watching television in bed and snacking after bedtime.

Your body balances hunger hormones during sleep, so sleep disruptions can make it challenging to eat a healthy amount and make healthful food choices during the day.

3. Accidents

The risk of work-related, motor vehicle, and otheraccidentsincreases when you do not get enough sleep. In 2022, more than 690 U.S. deaths resulted from drowsy driving.As nighttime light exposure decreases the amount of quality sleep and increases daytime drowsiness, it can also increase the risk of accidents.

4. Increased Risk of Chronic Illnesses

Nighttime light exposure and lack of sleep increase the risks of illness and chronic disease. For example, working the night shift and being exposed to light at night increases the risk ofcancer, cardiovascular disease, type 2 diabetes, and other conditions.Not getting enough quality sleep can weaken the immune system and increase the risk of many different conditions, both physical and mental.

How Getting Sunlight in the Morning Can Help You Sleep Better

Why Sleep Quantity and Quality Are Crucial

Your body and mind requiresleepto regulate hormones, prevent and recover from illness, and function properly. Sleep is just as important as nutrition and exercise, and not getting enough quality sleep can lead to physical andmental illness, along with other quality-of-life concerns.

Ways to Reduce Light Exposure at Bedtime

There are several ways to reduce light exposure at bedtime, making it easier to fall asleep, stay asleep, and getquality sleep, including:

What If I Can Only Sleep With the Light On?

Some lights are better than others when it comes to sleep. Try to use a light that is as dim as possible. It may help to get an adjustablelightand slowly adapt to a dimmer setting until it is no longer needed. The color of light matters, too; warm lights such as red, orange, and yellow are less likely to interfere as much with sleep as cool lights, especially blue.

What If My Kids Are Afraid of the Dark?

Being afraid of the dark is a natural phase of development for children. Having some light, especially temporarily, is okay as they overcome the fear. When a nightlight is needed, avoidblue lightand opt for a warmer color, such as red, orange, or yellow.

Other comfort methods may also help, such as talking about the fear or having a trusted caregiver in the room as they fall asleep.

Other Things That Can Disrupt Sleep

Loud noises can make it hard to fall asleep and can lead to abrupt waking up. Other sleep disruptors may go unnoticed. For example, stress interferes with sleep. Higher levels of stress are associated with fewer hours of total sleep and lower-quality sleep.

Other factors that can disrupt sleep include:

Summary

Exposure to light sources, especially bright lights, can interfere with sleep. This can be a challenge for anyone, but even more so for those who live in cities and populated areas. Light prevents melatonin production, making it harder to fall asleep, stay asleep, and get quality sleep. You can’t always control outside light, but there are ways to minimize exposure to ensure a good night’s sleep.

10 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Ohayon MM, Milesi C.Ohayon MM, Milesi C.Artificial outdoor nighttime lights associate with altered sleep behavior in the American general population.Sleep. 2016;39(6):1311-20. doi:10.5665/sleep.5860.Blume C, Garbazza C, Spitschan M.Effects of light on human circadian rhythms, sleep and mood.Somnologie. 2019;23(3):147-156. doi:10.1007/s11818-019-00215-xGooley JJ, Chamberlain K, Smith KA, et al.Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans.The Journal of Clinical Endocrinology & Metabolism. 2011;96(3):E463-E472. doi:10.1210/jc.2010-2098Obayashi K, Saeki K, Kurumatani N.Bedroom light exposure at night and the incidence of depressive symptoms: a longitudinal study of the Hijo-kyo cohort.Am J Epidemiol. 2018;187(3):427-434. doi:10.1093/aje/kwx290Bonmati-Carrion MA, Arguelles-Prieto R, Martinez-Madrid MJ, Reiter R, Hardeland R, Rol MA, Madrid JA.Protecting the melatonin rhythm through circadian healthy light exposure.Int J Mol Sci. 2014;15(12):23448-500. doi:10.3390/ijms151223448.Park YMM, White AJ, Jackson CL, Weinberg CR, Sandler DP.Association of exposure to artificial light at night while sleeping with risk of obesity in women.JAMA Intern Med. 2019;179(8):1061-1071. doi:10.1001/jamainternmed.2019.0571U.S. Department of Transportation.Overview of motor vehicle traffic crashes in 2022.Jefferson Health.How does nighttime light affect my health?Sleep Foundation.What color light helps you sleep?American Psychological Association.Stress and sleep.

10 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Ohayon MM, Milesi C.Ohayon MM, Milesi C.Artificial outdoor nighttime lights associate with altered sleep behavior in the American general population.Sleep. 2016;39(6):1311-20. doi:10.5665/sleep.5860.Blume C, Garbazza C, Spitschan M.Effects of light on human circadian rhythms, sleep and mood.Somnologie. 2019;23(3):147-156. doi:10.1007/s11818-019-00215-xGooley JJ, Chamberlain K, Smith KA, et al.Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans.The Journal of Clinical Endocrinology & Metabolism. 2011;96(3):E463-E472. doi:10.1210/jc.2010-2098Obayashi K, Saeki K, Kurumatani N.Bedroom light exposure at night and the incidence of depressive symptoms: a longitudinal study of the Hijo-kyo cohort.Am J Epidemiol. 2018;187(3):427-434. doi:10.1093/aje/kwx290Bonmati-Carrion MA, Arguelles-Prieto R, Martinez-Madrid MJ, Reiter R, Hardeland R, Rol MA, Madrid JA.Protecting the melatonin rhythm through circadian healthy light exposure.Int J Mol Sci. 2014;15(12):23448-500. doi:10.3390/ijms151223448.Park YMM, White AJ, Jackson CL, Weinberg CR, Sandler DP.Association of exposure to artificial light at night while sleeping with risk of obesity in women.JAMA Intern Med. 2019;179(8):1061-1071. doi:10.1001/jamainternmed.2019.0571U.S. Department of Transportation.Overview of motor vehicle traffic crashes in 2022.Jefferson Health.How does nighttime light affect my health?Sleep Foundation.What color light helps you sleep?American Psychological Association.Stress and sleep.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

Ohayon MM, Milesi C.Ohayon MM, Milesi C.Artificial outdoor nighttime lights associate with altered sleep behavior in the American general population.Sleep. 2016;39(6):1311-20. doi:10.5665/sleep.5860.Blume C, Garbazza C, Spitschan M.Effects of light on human circadian rhythms, sleep and mood.Somnologie. 2019;23(3):147-156. doi:10.1007/s11818-019-00215-xGooley JJ, Chamberlain K, Smith KA, et al.Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans.The Journal of Clinical Endocrinology & Metabolism. 2011;96(3):E463-E472. doi:10.1210/jc.2010-2098Obayashi K, Saeki K, Kurumatani N.Bedroom light exposure at night and the incidence of depressive symptoms: a longitudinal study of the Hijo-kyo cohort.Am J Epidemiol. 2018;187(3):427-434. doi:10.1093/aje/kwx290Bonmati-Carrion MA, Arguelles-Prieto R, Martinez-Madrid MJ, Reiter R, Hardeland R, Rol MA, Madrid JA.Protecting the melatonin rhythm through circadian healthy light exposure.Int J Mol Sci. 2014;15(12):23448-500. doi:10.3390/ijms151223448.Park YMM, White AJ, Jackson CL, Weinberg CR, Sandler DP.Association of exposure to artificial light at night while sleeping with risk of obesity in women.JAMA Intern Med. 2019;179(8):1061-1071. doi:10.1001/jamainternmed.2019.0571U.S. Department of Transportation.Overview of motor vehicle traffic crashes in 2022.Jefferson Health.How does nighttime light affect my health?Sleep Foundation.What color light helps you sleep?American Psychological Association.Stress and sleep.

Ohayon MM, Milesi C.Ohayon MM, Milesi C.Artificial outdoor nighttime lights associate with altered sleep behavior in the American general population.Sleep. 2016;39(6):1311-20. doi:10.5665/sleep.5860.

Blume C, Garbazza C, Spitschan M.Effects of light on human circadian rhythms, sleep and mood.Somnologie. 2019;23(3):147-156. doi:10.1007/s11818-019-00215-x

Gooley JJ, Chamberlain K, Smith KA, et al.Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans.The Journal of Clinical Endocrinology & Metabolism. 2011;96(3):E463-E472. doi:10.1210/jc.2010-2098

Obayashi K, Saeki K, Kurumatani N.Bedroom light exposure at night and the incidence of depressive symptoms: a longitudinal study of the Hijo-kyo cohort.Am J Epidemiol. 2018;187(3):427-434. doi:10.1093/aje/kwx290

Bonmati-Carrion MA, Arguelles-Prieto R, Martinez-Madrid MJ, Reiter R, Hardeland R, Rol MA, Madrid JA.Protecting the melatonin rhythm through circadian healthy light exposure.Int J Mol Sci. 2014;15(12):23448-500. doi:10.3390/ijms151223448.

Park YMM, White AJ, Jackson CL, Weinberg CR, Sandler DP.Association of exposure to artificial light at night while sleeping with risk of obesity in women.JAMA Intern Med. 2019;179(8):1061-1071. doi:10.1001/jamainternmed.2019.0571

U.S. Department of Transportation.Overview of motor vehicle traffic crashes in 2022.

Jefferson Health.How does nighttime light affect my health?

Sleep Foundation.What color light helps you sleep?

American Psychological Association.Stress and sleep.

Meet Our Medical Expert Board

Share Feedback

Was this page helpful?Thanks for your feedback!What is your feedback?OtherHelpfulReport an ErrorSubmit

Was this page helpful?

Thanks for your feedback!

What is your feedback?OtherHelpfulReport an ErrorSubmit

What is your feedback?