Why do you have to sleep in complete darkness

Modern bedrooms are full of light - Screen flickering and electronic clocks, street lighting. The problem is that the constant exposure to light leads to health problems.

To understand why light at night so detrimental effect on health, you can turn to history. While artificial illumination sources did not fill people's lives, he had only two "lamp": the day - the sun, at night - the stars and the moon, and, perhaps, the light from the fire.

This formed the human circadian rhythms, which, despite the change in lighting, still govern the state of sleep and wakefulness. Today nighttime artificial lighting is breaking the age-old human habit. It is less bright than sunlight, but brighter than the light from the moon and stars, and this triggers a cascade of biochemical reactions, including the production of hormones such as cortisol and melatonin.

Melatonin and cortisol

Melatonin - is the key to understanding why artificial lighting so bad for us. This hormone is produced in the pineal gland only on condition of absolute darkness and is responsible for the cycle of sleep and wakefulness. Melatonin reduces blood pressure, body temperature and blood glucose levels, that is, doing everything to ensure that the body calm, deep sleep.

In the human brain there is a part that is responsible for the biological clock - suprahiazmalnoe nucleus in the hypothalamus. This is a group of cells that respond to light and darkness, and transmits signals to the brain about when it's time to sleep and wake up.

In addition, suprahiazmalnoe core is responsible for changes in body temperature and cortisol production. At night, the amount of cortisol is reduced, allowing us to sleep, and in the afternoon - increased by adjusting the energy level.

All these processes are natural, but artificial lighting at night knocking them. The body reacts to light and increases the level of cortisol at night, so that the person finds it difficult to fall asleep. In addition, high levels of the hormone "stress" organism reduces insulin resistance and inflammation. As a result of the fact that cortisol is produced at the wrong time, disturbed sleep and appetite.

However, the level of hormones is regulated not only by the amount of light at the moment, but also by how much light you have received before.

Light before bedtime

Studies have shown that if a person spends time before going to bed in room light, melatonin is produced less than 90 minutes, compared to the dim light. If you sleep in room light, the melatonin levels decrease by 50%.

In this perspective, any light in your bedroom becomes a real problem, as tablets, smartphones, and energy-efficient lamps make it worse. The fact is that blue light from the LED is particularly strongly inhibits the production of melatonin.

Risk of cancer

Unfortunately, the violation of hormone provokes not only a bad dream, but also more serious, such as cancer. For 10 years, it conducted a study that proved that sleep by the 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 who rest in the dark. Researchers believe that it depends on the level of melatonin. Earlier experiments in vitro have shown that melatonin inhibits the growth of melanoma cells.

In another study, rats with breast cancer xenografts received a perfusion of blood from the women, who were sleeping in bright light, and by participating, sleeping in total darkness. Those rats that received the blood from the first, there was no improvement, whereas the second tumor was reduced.

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

Dim light, blue light, and depressed immunity

Unfortunately, the light in the bedroom at night does not have to be bright, to cause damage to health - enough even dim lighting. Studies conducted on hamsters have shown that dim light, kindled at night causes depression.

Hamsters, illuminated by dim light at night showed less interest in the sweet water, which they are so fond of. However, when the lights were removed, the hamsters returned to a previous state. In addition, the constant dim light in the bedroom bad for immunity because melatonin levels decrease, and immunological parameters deteriorate with him.

That is, if you have in your bedroom has electronic clock with lighting or other luminous devices, which work through the night, there is a serious reason to think so if you need them. And that's not to mention the constant light from a street light that penetrates into your window, when there is no heavy curtains.

And more health problems

Melatonin helps to fight against aging. It protects the brain cells against free radicals and prevents degenerative changes. Hormone functions as an antioxidant that protects cells within the brain, and can even be used by people over 40 years, as prevention of Parkinson's disease.

The next problem is a lack of melatonin - obesity. It is proved that light at night contributes to weight gain, disrupt the natural rhythms of the body. Experiments conducted on mice have shown that rodents subjected to nighttime lighting, gained weight more quickly than those that sleep in the dark, even though the amount of food and activity were similar.

What to do?

Summarizing all the above, we can derive a few rules:

1. Remove from her bedroom all that can glow in the dark, including watches, electronics, gadgets and all sorts of relaxing lamps such as "starry sky", which you leave to burn at night.
2. Turn off the lights at night, even the dim bedside lamp.
3. Hang thick curtains or blinds to the street lighting does not penetrate into the room.
4. Do not read before going to bed on your tablet or smartphone and do not take them to the bedroom.
5. Try to change jobs at this, where there is no night shifts.