And they will study whether it is involving in controlling sleep quantity alone, or also what scientists call the "wakefulness-behavioral drive."

VOA: special.2009.08.26

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

And then you do twenty-plus miles the next day,you sleep in a tent, you gotta wake up and you got to do it again.

VOA: special.2009.11.02

He died in his sleep in February,nineteen twenty-two, at the age of eighty-one.

VOA: special.2010.03.17

You can sleep on it.If you still feel like going in the morning, - I'll take you to the airport.- No. I want to drive.

VOA: standard.other