Most adults need 6-8 hours of sleep at night to feel refreshed in the morning. Partinen says people should go to bed 10-15 minutes before planning to fall asleep, making finding the right bedtime pure mathematics.
"If you want to wake up at 7 and need seven and a half hours of shut-eye, you should be in bed at quarter past 11," calculates Partinen.
Trying to catch an early night may only make you toss and turn in bed as your body is not ready to go to sleep. Partinen recommends setting the alarm clock earlier in the morning, which will help you fall asleep as soon as your head hits the pillow the following night.
Biological reasons
Partinen agrees with Professor Rafael Pelayo, a sleep expert at the Stanford School of Medicine, on the reasons behind people tending to wake up during the night. Speaking with Wall Street Journal, Pelayo said that problems in falling asleep and sleeping through the night stem from biological reasons as broken sleep has been beneficial in the course of human history.
People go through periods of lighter sleep during the night, with sleep consisting of 90-minute cycles with alternating stages of deep and lighter sleep. Pelayo says that this sleep cycle has evolved from the need to stay alert also during the night. People have stirred regularly to check that their surroundings are still safe, before falling back to sleep very quickly.
This ability to go back to sleep immediately explains why mothers can wake up to nurse a baby and then nod off again. When people feel threatened, they are more likely to wake up during the period of lighter sleep and feel unable to go back to sleep. The biological need to get some zzz's will help even a stressed and anxious person to fall asleep, but sleep often becomes disturbed early in the morning.