Sleep is as important as nutrition. When we make mistakes, it does not just make itself visible externally. Too little sleep can lead to obesity, insulin resistance, strokes, memory problems or heart disease. And yet we give the subject of "sleep" – especially "enough sleep" too little attention. But how do we know when to sleep well? To find out how much sleep your body needs, you need to do this test: Step 1:
Choose a weekend or days to sleep in. Do not spend an awkward time waking up by tapping on the phone or watching TV. It's best to go to bed before midnight! Step 2:
Sleep until you wake up by yourself. So you do not have to set an alarm. Warning: It can happen that you sleep soundly for a long time if you have a lack of sleep and need to catch up on sleep. Step 3:
When your lack of sleep is balanced, you wake up a little earlier. It is important that you go to bed at the same time every day. Do not set an alarm clock. When your body is settled, you should wake up at about the same time each day. Step 4:
Now you know how many hours of sleep your body needs to feel fit and well rested the next day. Note: This guide is calculated after a "normal" day. If you have days when you have a lot of stress at work or are exposed to physical exertion, your body may need even more sleep.

The best time to go to sleep

Which age group needs how much sleep?

Newborns 0 – 3 months: 14 to 17 hours
Babies 4 – 11 months: 12 to 15 hours
Infants 1 – 2 years: 11 to 14 hours
Kindergarten children 3 – 5 years: 10 to 13 hours
Schoolchildren 6 – 13 years: 9 to 11 hours
Teenagers 14 – 17 years: 8 to 10 hours
Young adults 18 – 25 years: 7 to 9 hours
Adults 26 – 64 years: 7 to 9 hours
Older 65+ years: 7 to 8 hours Source: The Sleep Revolution, Arianna Huffington

This app tells you more about your sleep

The app "Sleep Cycle Alarm Clock" recognizes with the microphone and a motion sensor all your sleep phases. The smart alarm clock will wake you up in the most appropriate sleep phase. You will also get detailed statistics about your sleep behavior. How many hours did you sleep? Did you sleep peacefully? Which day did you sleep best?
The app is available for free for iOs.