Reasons Why You Shouldn’t Sleep With Light On

Research shows that sleeping with artificial light on increase the risk of obesity, chronic illness and sickness, including cancer. Research shows that sleeping with artificial light on increase the risk of obesity, chronic illness and sickness, including cancer.


The pineal gland (an endocrine gland in the human brain) produces a hormone called melatonin. It regulates our body’s normal sleep-wake cycle. Besides, it also synchronizes the body vital functions such as blood pressure regulation, reproduction, and preventing inflammation.

Melatonin influences sleep by sending signals to the brain that the time to rest. This signal initiates the body’s physiological preparations for sleep – muscles to relax, feelings of drowsiness increase, body temperature drops. Melatonin levels naturally rise during the early evening as darkness falls and continue to increase until 3 am.

Public Health Malaysia emphasize

Public Health Malaysia shared America’s research recently, it shows that if sleeping with a light on will increase the female’s weight.  America Medical Magazine – Internal Medicine published this research in June of 2019. It illustrates the relationship between artificial light and weight.

America’s research

America National Institutes of Health studied 43722 females, aged from 35 to 74 years old. These women no pregnant, no work night shift, and also no chronic related history illness.

They completed a questionnaire about their sleeping mode of whether off light, on light, open night lamp, penetration of light from outdoor or open TV when they are sleeping. Besides, they provide their weights, heights, waistline, hipline, and body mass index.

The researchers collected data from them after 5 years. They found that the women who turn on the light and open TV have a higher probability of getting weight than others. While having a night lamp has no relation to the increase in weight.


Researchers concluded that humans already adapted the day bright and night dark environment. If humans are being exposed to artificial light at night, the human body will change the percentage of melatonin produced.  It will thus lead to irregular physiological rhythm, boost the probability of obesity, and so on.

Dr Joshua Gooley Research

Dr Joshua Gooley of BRIGHAM AND Women’s Hospital and Harvard Medical School studied 116 volunteers, aged from 18 to 30. They are exposed to room light and dim light for 8 hours before sleeping for 5 consecutive days. The result showed that light will shorten the production of melatonin by 90 minutes and also reduce the amount by 50%.

Light lead to Low Melatonin at Night

When the body has low melatonin, we hard to make our brain to have a deeper sleep. Thus, sleep quality suffered. It will contribute to some serious consequences such as depression, moodiness, irritability, hyperactivity (for children), and even cancer.

Other than that, it will increase the risk of chronic illnesses – hypertension, heart disease, Type2 diabetes as melatonin regulates these body’s functions. In the other words, sleeping with the light on causes humans easier to get migraines in the daytime and this will lead and develop into insomnia.


More information about:

Content Sources:

  1. Too Much Light: Ruining Not Just Your Sleep But Your Health Too
  2. Turn Off the Lights (and the TV) Before Going to Sleep



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