Studies have shown that over time, most humans need eight to eight and a half hours of sleep for the best health.

VOA: special.2009.08.26

The next time you think about going without sleep, consider this: Laboratory animals that are kept awake for long periods of time ...die.

VOA: special.2009.08.26

The amount of sleep was based on their reporting of a child's usual bedtime and wake time.

VOA: special.2010.06.09

A new study found better results in four-year-olds who go to bed around the same time every night and sleep at least eleven hours.

VOA: special.2010.06.09

He says he realized it was time to find a separate space where the poets could gather and he could still get some sleep.

VOA: special.2009.04.27

And to prepare himself, he went without sleep for long periods of time.

VOA: special.2009.03.18

Sometimes people sleep for a short time during the day.

VOA: special.2009.09.27