"Your ancestors would be very surprised to learn that their descendants slept 8 hours altogether, because before 300 - 400 years ago man's sleep was divided into two parts," says Professor of the Historical Faculty of Virginia Polytechnic Institute, Roger Ekirch.

People went to bed 2 hours after sunset and woke up after about 4 hours. Then they either made love, talked together, or prayed and went back to sleep, which also lasted 4 hours.

"Do you feel I made it up? Nothing like that, "says Professor Ekirch in his book A night in times past and presents us with more than 500 documents about the split sleep. We can also find it in Homer's Odyssey, in various personal diaries, court records and other sources.

For example, in 15th-century prayer books, we can find prayers that relate to the waking hours of the night between periods of sleep. And a collection of medical recommendations, published in France in the 16th century, advises married couples to conceive a child after the first sleep, when people enjoy it more than at the end of the working day.

The scientist is convinced that our ancestors spent far more time in bed than we think. That's because their work day was dependent on the sun - how long the light was.

Our body has struggled to sleep over the long winter night, so sleep was divided into two phases. Even wealthy people who could afford to burn candles all night had no reason to change the custom.

According to Ekirch, mentions of the first and second phases of sleep began to disappear at the end of the 17th century. The reforms and counter-reformations of the churches were partly to blame. Protestants and Catholics were then forced to meet for prayer in secret and at night, when most people did not go out. After their persecution ended, the habit of being awake by candlelight long into the night.

Another factor that interfered with sleep was street lighting. In 1667, wax candles began to be installed in the streets of Paris in street lamps (for the first time in the world). After two years, the lighting also appeared in Amsterdam, but they already used oil lamps there.

Then came the Industrial Revolution, the working day became longer, and sleep "more than twice" became a luxury. Divided sleep can also be found in Leo Tolstoy's novel War and Peace, where the old prince Bolkonsky says "after lunch the sleep is silver and until lunch it is golden".

As we approach the 20th century, two-phase sleep becomes a "survival" and most people adapt to an 8-hour sleep in one piece. But if you wake up unjustifiably in the middle of the night, don't panic, nothing terrible is happening, only the old habit is remembered from the depths of genetics.

It is not good to try to fall asleep at any cost, you will not succeed. Remember the ancestor's customs and deal with something. You do not have to pray or love. You can read or sleep. After some time you will surely be asleep.

By the way, researchers claim that a 12-hour sleep with a 2-3-hour break is ideal for gaining strength, relieving stress and promoting creativity.

In the 90s, the American psychiatrist Thomas Wehr performed an interesting experiment. For 15 volunteers, he mimicked the conditions in which people lived until artificial lighting appeared. The subjects were in a room where the lights were turned off at 18:00 in the evening until 8:00 in the morning. At first, the participants slept for up to 11 hours (probably compensating for the previous lack of sleep) and then unexpectedly switched to two-phase sleep, which Wehr concluded to be natural. Whether this is the case or not, you can try it for yourself…