A National Sleep Foundation survey of 1,000 people found participants average six hours and 40 minutes of sleep a night on weeknights, even though people estimated they'd need about 40 more minutes of sleep to be at their best.

About one-third said they've had fallen asleep or become very sleepy at work in the past month.

Last week, the chairman of the Nuclear Regulatory Commission acknowledged it should have done more to investigate a tip that security guards routinely took naps while on the job at a Pennsylvania nuclear plant.

Why so tired? The survey finds workdays are getting longer and time spent working from home averages close to four-and-a-half hours each week.

People are trying to squeeze in more family time, too.

The average wakeup time is 5:35 in the morning. Average bedtime is 10:53 p.m.