Difference Between Sleeping With The Lights Switched On And Lights Switched Off

Jan 02, 2019

If your bedroom is like most other bedrooms, it is never completely dark. There may be light generated by a bedside alarm clock, a smartphone charging on a bedside table, a TV, a laptop or other items.

You may think that a modest amount of light in an otherwise darkened bedroom would not be a significant factor in the quality of your sleep.

However, many doctors and sleep experts along with National Sleep Foundation agree that it is best to sleep in total darkness.

How Our Ancestors Slept


When you look at what is healthiest for the human body, it is essential to see what the human body initially experienced and had adapted to. The inventions of the lightbulb and electronics, in general, are relatively recent inventions compared to the overall timeline of human history. For millions of years, our ancestors relied on Mother Nature to provide the primary light source.

This means that the only light sources at night may have been the moon and the stars. Over countless generations, the human body’s biology has adapted to this. The human body simply has not had ample time to adjust to sleeping with artificial light sources nearby, so it is affected by these lights sources.


The Important Role Played by Melatonin


Melatonin is a hormone produced in the human body that directly affects the regularity of the sleep-wake cycle. It is produced in the pineal gland, which is located in a central location in the brain. The pineal gland senses when nighttime has arrived by exposure to light, and it naturally increases the production of melatonin in the body. This boost in melatonin helps you to fall asleep quickly and naturally.

The Impact of Artificial Light on Melatonin Production

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When your bedroom is not entirely dark, the pineal gland can get confused. It may not sense that it is night and that it needs to produce more melatonin. Light from a TV, a clock radio, a lightbulb in a small nightlight and from other sources may impact melatonin production. Even light streaming in your bedroom window from outside can make your room brighter than your body needs it to be for high-quality sleep.

In the study, "Exposure to Room Light before Bedtime Suppresses Melatonin Onset and Shortens Melatonin Duration in Humans", published in The National Center for Biotechnology Information, participants were exposed to dim light and regular room light 8 hours before their bedtime for five days. It was found that room light has a significant and suppressive impact on melatonin levels and may reduce the body's natural understanding of night duration. Therefore, exposing oneself to lighting before bed disrupts melatonin production and could have an adverse effect on sleep cycle.

Even when you do fall asleep, the lack of a significant amount of melatonin in the body may, unfortunately, reduce the quality of sleep that you get. You may wake up feeling fatigued on a regular basis.

The Impact of Poor Sleep Quality on Health

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The disruption of melatonin production in the pineal gland has much more significant effects than just leaving you feeling fatigued. A lack of focus and general inattentiveness may result in more accidents, lower productivity and more. It also has been equated with weight gain, depression and issues with reproductive health. These issues, in turn, are related to heart disease, diabetes and even some types of cancer.

Even if you are getting the recommended seven to nine hours of sleep each night, the quality of that sleep may be reduced as a result of unnecessary lighting in your home. With this in mind, it makes sense to identify all sources of extra light and to make your room as dark as possible. In addition to powering down your electronics, you may also need to invest in blackout curtains.


Have you been struggling with regular fatigue, weight gain, difficulty staying focused and other similar issues? Have you tried making your bedroom darker at night? This simple change to your sleeping environment may have a significant impact on sleep quality and your overall health. Provide feedback about your experiences in the spaces below for other readers to learn from and pass the information on to others as well.

Our content is created to the best of our knowledge, yet it is of general nature and cannot in any way substitute an individual consultation by your doctor. Your health is important to us!