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How Light Can Affect Your Sleep Cycles

January 04, 2018

We all crave it, yet few of us get enough – or the right kind of – sleep.

The National Institutes of Health reports that 50-70 million Americans are affected by chronic sleep disorders and intermittent sleep problems.

This leads to more than cranky days; it can lead to some serious health problems.

The simple fact is that poor sleep leads to poor health. A lack of quality sleep has been linked to everything from weight gain and moodiness to heart disease and diabetes.

Without the right amount of sleep, the perfect timing of sleep, and the proper intensity of sleep, our bodies pay a price.

How Sleep Works

You may think of sleep as a time to recharge your energy reserves. While this may be true, there is more to sleep than that.

Our body sleeps to rejuvenate, heal, and simply rest overworked muscles and organs. This is done through a systematic cycling approach.

The human body uses two main kinds of sleep: rapid eye movement (REM) and non-rapid eye movement (NREM) to give the body’s systems and organs the time it needs to rejuvenate.

Each sleep stage is also broken down into smaller phases or cycles. Spend too much or too little time in each of these stages and you will feel the effects.

What Affects Sleep Cycles

There are a lot of factors that can affect a person’s sleep cycles:

  • health
  • temperature
  • noise
  • emotions
  • light

While almost anything can disrupt a good night’s sleep, light seems to have a dramatic effect on how a person sleeps and to what degree of quality sleep they experience.

Light to Blame for Chronic Tiredness

Can light really affect the way you sleep? Yes, and in more ways than one.

Light and darkness tell your body when to rest. Exposing yourself to artificial light after dark sends wake-up messages to your brain which can make it difficult (if not impossible) to fall or stay asleep.

This can keep you from entering the right sleep cycles, at the right time, during the night.

In a 2012 bedroom poll conducted by the National Sleep Foundation, it was reported that 73% of Americans rated a dark room as important to getting a good night’s sleep.

Those findings have been backed up time and time again by researchers who study sleep on a regular basis.

Another study, published in the Journal of Clinical Endocrinology and Metabolism, conducted just a year earlier, found that exposure to room light suppressed melatonin levels in 99% of participants and shortened melatonin levels in those same participants for about 90 minutes each night.

Following the study, the researchers announced that, “These findings indicate that room light exerts a profound suppressive effect on melatonin levels and shortens the body’s internal representations of night duration. Hence, chronically exposing oneself to electrical lights in the late evening hours disrupts melatonin significantly and could therefore potentially affect sleep, blood pressure, and glucose homeostasis.”

Melatonin is an essential hormone to regulating sleep cycles. It helps the body distinguish between daytime and nighttime and is a major signaler to the brain to begin preparing the body for sleep.

Without the proper release of this important hormone, your body has no idea that it is time for rest. Worse yet, it is unable to do so.

The Biggest Light Culprits to a Good Night’s Sleep

There are a lot of light factors that can affect your sleep patterns.

Blue light seems to be the worst. Given off by computer screens and cell phones, blue wavelengths in the range of 460 nanometers on the electromagnetic spectrum keep people more charged than other sources of light.

The National Sleep Foundation reports that 95% of people use a computer, cell phone or video game within an hour of bedtime, which may be one reason why so many people find it difficult to fall asleep when their head hits the pillow.

It isn’t stress, worry, or other factors keeping you awake – it is the blue light from your alarm clock telling your brain to stay alert!

Of course, any type of artificial light can disrupt your sleep cycles.

In addition, not getting enough natural light exposure during the day can also send your body’s natural rhythms out of whack.

Is Sleeping with the Lights on Dangerous?

Poor sleep leads to poor health.

The Institute of Medicine says in its report, Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem, that “hundreds of billions of dollars are spent every year on direct medical costs related to sleep disorders.”

This includes doctor visits, hospital services, and medications. Just some of the conditions associated with sleep problems include:

  • diabetes
  • heart attacks
  • stroke
  • depression
  • obesity
  • high blood pressure
  • auto-immune disorders


Simple Ways to Darken Your Bedroom

The darker your bedroom, the better sleep you will experience. Not sure how to cut that light pollution? Here are a few simple tips:

  • Install darkening shades in your bedroom.
  • Wear a sleeping mask at night.
  • Use low-wattage incandescent lamps in areas you use a few hours before bedtime.
  • Avoid using computers, cell phones, and TV’s within 1-2 hours of going to bed.
  • Check windows for streetlight and porch light infiltration.
  • Cover power buttons on electronics in the sleeping area.
  • Replace blue or green lighted electronics (like digital clock) with amber looking ones.
  • Go to bed at the same time each light (this helps to synchronize your sleep cycles).

If you have ever felt drained and tired by midday, you know the importance of getting a good night’s sleep. Now you know why (even if you sleep long enough each night) your body may not getting a complete rest.

The light you expose yourself to all day and evening can be the culprit.Be sure to get enough natural light exposure during daylight hours, and limit your artificial light exposure at night.

Before long you will notice that your body will recognize when it’s time to rest and you will awaken each morning feeling refreshed and ready for the day.


Colton, H.R., & Altevogt, B.M.(Eds.) (2006) Sleep Disorders & Sleep Deprivation: An Unmet Public Health Problem. doi: 10.17226/11617
Gooley, J., Chamberlain, K., Smith, K.A., Rajaratnam, S.M., Van Reen, E., Zeitzer, J.M., et al. (2011, March) Exposure to room light suppresses melatonin onset and shortens melatonin duration in humans. The Journal of Clinical Endocrinology and Metabolism, 96 (3, E463-E472. doi: 10.1210/jc.2010-2098
National Sleep Foundation Bedroom Poll (2012) Retrieved from
National Sleep Foundation Sleep in America Poll: Communications Technology and Sleep (2011, March) Retrieved from