How many time for normal human sleeping?

Depends on age: Adults need 7-8 hours. Teens 8-10 hours.

7 1/2 to 8 hours: the amount of sleep an adult needs is variable but somewhere between 7 1/2 to 8 hours.

Six to nine hours.: Technically speaking, six to nine hours at intervals of 90 minutes which matches your awakening time to a lighter stage of sleep. So either 6, 7.5, or 9 hours per night.

Depends: Normal sleeping time is usually 6-8 hours however some people need more to feel rested. If you feel like you need to nap during the day, you probably are sleep deprived and should seek out medical attention.

Depends: 6 - 9 hours but if you feel well and not tired during the day it is likely OK. Quantity is important but quality matters also. Sleep hygiene is paramount to get enough good REM time. Physical activity, good healthy balanced diet, avoid caffeine and sugary foods in the 2nd half of the day, no smoking and avoid alcohol. Lastly only get under the covers when you want to sleep