Experiments suggest two-phase sleep is natural

Although we normally sleep through the whole night, experts on sleeping now think that this is unnatural and may not be good for us.

In an experiment carried out two decades ago, a group of people were put into a dark room for fourteen hours a day. Towards the end of the experiment most of them developed a sleeping pattern. They slept for four hours, were then awake for a few hours and slept again for four hours. This opposed the general theory that uninterrupted sleeping for eight hours is normal.

History shows that sleeping in two phases was normal for a long time. During the time when they were awake people got up, strolled around or went smoking. Some people stayed in bed, prayed or read something. Historical prayer books contain special prayers that people said between sleeping periods.

Evidence showing the two phases of our nightly sleep started disappearing at the beginning of the Industrial Revolution. By the 20th century the idea of splitting up nightly sleep vanished from western society.

Sleeping Child

Sleeping Child


During the Middle Ages people were afraid of night and stayed indoors. It was a time when criminals, prostitutes and drunks roamed the streets. Later on people got accustomed to staying up after sunset. When street lighting became widespread people began to socialize, go to inns or pubs. Paris and Amsterdam became the first cities to introduce street lighting. By the end of the 17th century over 50 European cities were lit up at night.

Over the past two centuries people have adapted to eight hours of sleep, but waking up at least once during a night’s sleep seems to be quite normal. We wake up if we are stressed or have problems. Sometimes we panic or have a nightmare. Many doctors say this is normal and proves the theory of our two-phase sleep pattern. Other doctors suggest that waking up between two sleep phases could have regulated stress in a natural way. Historic studies show that people may have woken up after dreaming and then thought about their dreams.

Today we spend less time thinking about our other problems, so stress, anxiety and depression has increased.



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  • accustomed to = to get used to
  • adapt to = get used to
  • although = while
  • anxiety = the feeling of being very worried about something
  • carry out = do
  • century = a hundred years
  • contain = have in them
  • decade = a period of ten years
  • depression = sadness
  • develop = build up
  • disappear = go away
  • evidence = proof, facts that show something is true
  • increase = to go up
  • indoors = in the house
  • Industrial Revolution = period starting at the end of the 18 th century when machines were invented and people started working in factories
  • inn = restaurant, bar
  • introduce = to start having
  • nightmare = a bad and frightening dream
  • oppose = to be against
  • pattern = the regular way in which something happens
  • phase = part
  • pray = to say words to god
  • prove = show
  • regulate = control
  • roam = wander around, without knowing where you really want to go
  • socialize = go out and meet other people
  • special = certain, individual
  • split up = divide, separate
  • stress = to feel pressure and have problems
  • stroll = wander around
  • suggest = put forward, say
  • towards = near, at
  • uninterrupted =non-stop ; without a break
  • unnatural = not normal
  • vanish = disappear, go away
  • widespread = common