Table of contents:

Why sleep in complete darkness
Why sleep in complete darkness

There are good reasons to hang blackout curtains at home, turn off the lights at night, and not read on your tablet before bed. Sleeping in complete darkness keeps you young, reduces your risk of cancer, and supports your immune system.

Why sleep in complete darkness
Why sleep in complete darkness

Modern bedrooms are filled with light - the flickering of a monitor and electronic clock, street lighting. The problem is that constant exposure to light leads to health problems.

To understand why light at night is detrimental to health, you can turn to history. Until artificial sources of illumination filled a person's life, there were only two "lamps": during the day - the sun, and at night - the stars, the moon and a fire.

This formed the human circadian rhythms, which, despite the change in lighting, still regulate the states of sleep and wakefulness. Today, artificial lighting at night breaks centuries of human habits. Not as bright as sunlight, but brighter than light from the moon and stars, it triggers a whole cascade of biochemical reactions, including the production of cortisol and melatonin.

Melatonin and cortisol

Melatonin production is key to understanding why artificial lighting is so harmful. This hormone is only produced in the pineal gland when it is completely dark and is responsible for the sleep-wake cycles. Melatonin lowers blood pressure, body temperature and blood glucose levels, which means it does everything to provide the body with a restful deep sleep.

The human brain has a part that is responsible for the biological clock - the suprachiasmatic nucleus in the hypothalamus. This is a group of cells that reacts to darkness and light, and sends signals to the brain when it is time to fall asleep and wake up.

In addition, the suprachiasmatic nucleus is responsible for the change in body temperature and the production of cortisol. During the dark hours of the day, the amount of cortisol decreases, allowing us to sleep, and during the day it rises, regulating the level of energy.

All these processes are natural, but artificial lighting at night confuses them. The body reacts to light and raises cortisol levels at night, making it more difficult for a person to fall asleep. In addition, high levels of the "stress hormone" reduce the body's resistance to insulin and inflammation. As a result of the fact that cortisol is not produced on time, appetite and sleep are disturbed.

However, hormone levels are regulated not only by the amount of light at the moment, but also by how much light you received before.

Light before bed

Studies have shown that spending time in dim light instead of room light before bed can increase the time it takes for melatonin to be produced by 90 minutes. Sleeping in room light reduces melatonin levels by 50%.

From this angle, any light in the bedroom becomes a real problem, and tablets, smartphones and energy efficient lamps only make it worse. Blue light from LEDs is particularly effective in suppressing melatonin production.

Danger of cancer

Unfortunately, the violation of hormone production not only provokes poor sleep, but also leads to more serious consequences. For 10 years, a study has been conducted that has shown that sleeping with light increases the risk of cancer.

Participants in the experiment who slept in the light were 22% more likely to develop breast cancer than women resting in complete darkness. Researchers believe it depends on melatonin levels. Even earlier, in vitro experiments proved that melatonin blocks the growth of melanoma cells.

In another study, rats with breast cancer xenografts were perfused with the blood of women who slept in bright light and participants who slept in complete darkness. The rats that received the blood from the former showed no improvement, while the latter did not see the tumor shrink.

Based on the data from these studies, we can say that sleeping in the dark is the prevention of cancer and can only sympathize with the people who work the night shift.

Even dim light is harmful

Unfortunately, bedroom lights don't have to be bright at night to be detrimental to health. Even dim lighting is enough. Hamster studies have shown that dim light at night causes depression.

Hamsters exposed to dim light at night showed less interest in the sweet water they love so much. However, when the lights were removed, the hamsters returned to their previous state. In addition, constant dim light in the bedroom has a negative effect on immunity, since the level of melatonin decreases, and along with it, immunological parameters deteriorate.

That is, if you have a backlit electronic clock or other luminous devices in your bedroom that works all night, this is a reason to think about whether they are so necessary. And this is not to mention the constant light from street lighting that enters the window when there are no blackout curtains.

And more health problems

Melatonin helps fight aging. It protects brain cells from free radicals and prevents degenerative changes. The hormone acts as an antioxidant that provides protection inside brain cells, and can be used by people over 40 years of age as a prophylaxis for Parkinson's disease.

Another problem from a lack of melatonin is obesity. Light at night has been shown to promote weight gain by disrupting the body's natural rhythms. Experiments on mice have shown that rodents exposed to night light gained weight much faster than those who slept in the dark. Although the amount of food and activity was the same.

What to do?

To summarize, here are a few rules:

  1. Remove from the bedroom anything that glows in the dark, including clocks, electronic devices, gadgets, and any kind of relaxing "starry sky" lamps that you leave on overnight.
  2. Turn off all lights at night, even the dimmest night lights.
  3. Install blackout curtains or close blinds to prevent street lighting from entering the room.
  4. Don't read on your tablet or smartphone before bed, or take them into the bedroom at all.
  5. Try to change your job to one where there are no night shifts.