Roughly one-third of American workers said they had fallen asleep or become very sleepy at work in the past month, according to a survey released Monday. The survey of 1,000 people by the National Sleep Foundation found participants average six hours and 40 minutes of sleep a night on weeknights, even though they estimated they'd need roughly another 40 minutes of sleep to be at their best. Just how big a deal that is depends, of course, on one's job. 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. It wasn't until a videotape of guards sleeping in a "ready room" at the Peach Bottom plant in south-central Pennsylvania surfaced several months after it got the tip that the NRC announced in September a special investigation. While sleepy workers know they're not performing as well as they could during the day, work is what's keeping them up nights, according to the survey, which found workdays are getting longer and time spent working from home averages close to 41â„2 hours each week. It seems people are also trying to squeeze in more time for themselves and their families, even if it means less sleep. The average wake up is at 5:35 a.m. and it's followed by about two hours and 15 minutes at home before heading out to work, according to the survey. Average bedtime is 10:53.