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What happens when I sleep?

While you sleep and “do nothing” your body is rebooting many of its systems and carrying out all sorts of maintenance. It’s like your body is pampering itself and you don’t have to do anything but sleep.

A couple wearing matching pyjamas sprawl across a double bed, deep in sleep.
A couple wearing matching pyjamas sprawl across a double bed, deep in sleep.

Your body reboots when you sleep

Sleep is vital for both our physical and emotional well-being. Physically, the body goes through a restorative process that affects the digestive system, the immune system and the cardiovascular system.

It’s actually been proven that a lack of sleep increases the level of “hunger hormone”, making us eat more than we should and thus increasing the risk for all sorts of diseases. Lack of sleep might increase the risk of getting heart disease and even Alzheimer’s disease.

Sleep is good for your brain

Getting the right amount of sleep is also crucial when it comes to emotional and cognitive functions. Studies show a clear connection between lack of sleep and depression. Not getting enough sleep can also make us less empathetic. This is believed to be the result of over activity in certain parts of the brain. The brain needs to be unplugged for several hours to be in sync with itself.

The hours that we sleep allow the brain to catch up and prepare itself for the day after. The positive effects of good sleep are also affecting our ability to focus and concentrate, to remember, to solve problems and to motivate ourselves.

Good sleep is a lovely reward but also a necessity for a balanced and happy life.

How much sleep do I need?

As we get older, our need for sleep actually decreases. As newborns and infants we need as much as 17 hours of sleep per day. Later in life, when we're between 18 and 64 our bodies are perfectly happy with 7 to 9 hours per day. Typically, our need for sleep looks like this:

  • Newborns, 0-3 months: 14-17 hours/day
  • Infants, 4-11 months: 12-15 hours
  • Toddlers, 1-2 years: 11-14 hours
  • Preschoolers, 3-5 years: 9-11 hours
  • School-age children, 6-13 years: 9-11 hours
  • Teenagers, 14-17 years: 8-10 hours
  • Adults, 18-64 years: 7-9 hours
  • Older adults, 65+: 7-8 hours

The four stages of sleep

Sleep consists of four sleep stages that always occur in the same order. It starts with light sleep, which is the stage between being awake and falling asleep. As this happens your heartbeat and your breathing slows down and your muscles relax.

The next stage is when the body prepares itself for deep sleep. Now, your heartbeat and your breathing slows down even more – and your brain activity is also slow.

The third stage is called deep sleep. During this stage your body is completely relaxed and your brain is running on idle. The repair and restoration processes in your body are taking place.

The last stage is when we enter the REM-stage or the dreaming stage. Our eyes are now moving rapidly from side to side and our muscles are paralysed. This is the last stage and the complete cycle has now lasted for approximately 60 to 90 minutes.

After this, the fourth stage, it starts all over again. Your body takes a brief pause, when you actually wake up, and then goes back into the sleep cycle starting with stage one. The whole cycle is repeated 4 or 5 times every night. So if you wake up in the middle of the night, don’t worry, it’s completely natural.

If we get the hours of sleep that we need, we will wake up feeling fresh and well-rested. If our sleep is interrupted and we wake up in the middle of a sleep cycle, it's the other way around. We feel tired, irritated and not too happy about having to get out of bed.