Jan. 10, 2006 -- Got a decent amount of sleep last night? Even so, your mental skills still might not have been all that sharp first thing this morning.
It's that woozy time when your eyes are open, but you're not exactly alert. All things being equal, you might rather roll over and hit the snooze button than put your feet on the floor and start the day.
The brief report, published as a research letter in The Journal of the American Medical Association, comes from researchers including Kevin Wright, PhD, of the Sleep and Chronobiology Laboratory at the University of Colorado at Boulder.
"For a short period, at least, the effects of sleep inertia may be as bad as or worse than being legally drunk," Wright says in a news release.
Wright's small study included eight men and one woman. They were about 29 years old, on average, and were paid for their participation.
None had sleep disorders. They also hadn't recently crossed time zones or done shift work.
Next, participants spent a week at a sleep lab. For the first six nights, they got eight hours of sleep following their normal bedtimes.
During the days, participants spent some time adding double-digit numbers together. They weren't just killing time. That adding skill was supposed to come in handy later on.