On The Early Show Thursday, medical correspondent Dr. Emily Senay reported on both.
In the first, Senay said, researchers put a detailed questionnaire online, and got more than 35,000 responses. What they wanted to know was how many people had come very close to being involved in traffic accidents at times when they felt sleepy behind the wheel. More than 18 percent said they could recall at least one incident in which they'd barely escaped being in a crash.
The researchers also gathered information on how many near-misses these drivers had had — some remembered as many as four — as well as how many times they'd gotten into accidents.
The numbers showed that the more near misses a person experienced, the more likely that person also was to be involved in an actual crash. People who could recall four near-misses were 87 percent more likely to have been in a crash than people who hadn't had any close calls.
So, if you've been involved in near-misses behind the wheel, the results suggest that you shouldn't assume that somehow you were sharp enough to avoid a crash despite being sleepy. Instead, Senay pointed out, you should take these near-misses as a sign that you've just been lucky, and chances are strong that your luck will run out if you don't stop driving when you're sleepy.
The American Academy of Sleep Medicine says you shouldn't skimp on the sleep you get at night. Getting seven to eight hours really does keep you more alert when it counts. If you are sleepy on the road, pull over and take a nap. Even 15 to 20 minutes can help. Caffeine improves alertness on the road. And don't drive late at night. After midnight is our natural time to be asleep, and that makes it the time when drowsiness can affect our driving the most.
The other study showed a lack of sleep affecting choices we make.
In this one, 26 members of the military who were well-rested were given a questionnaire about very hard decisions they might be called on to make. They included battlefield situations, or tough choices that might face a doctor, or the lengths to which a person might need to go in order to feed his family. There was no right answer to these questions, but they all involved extremely hard choices.
These people were then kept awake for 53 hours straight, and given the same questionnaire when they were exhausted. When they were sleep-deprived, they tended to be much slower in making their decisions, and sometimes made different decisions.
The authors say their findings may be relevant in situations were people are forced to stay awake a long time, people such as doctors, nurses and police officers whose judgments often can involve matters of life or death. It also tells the rest of us who feel the urge to push forward without sleep from time to time, that our exhaustion might have serious consequences that go beyond the way we feel.
Both studies appeared in the journal SLEEP.