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QUESTION

Can you be asleep with your eyes open? There are anecdotal stories of people apparently being sound asleep in bed but their eyes are wide open. And can someone drive a car or operate a machine and doze off while their eyes remain open?

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ANSWER

These two cases are similar, but they represent two very different sleep conditions.

The first - being asleep at night with the eyes open - is probably an example of parasomnia. Parasomnia, meaning "around sleep," refers to a number of behaviours that occur during sleep including sleepwalking, talking, grinding the teeth and opening the eyes while asleep.

Parasomnias are more common in children, but do occur in adults and can be brought on by stress or alcohol. The problem with parasomnias is that they can disrupt our sleep, causing us to awaken unrefreshed and lead to daytime sleepiness. The good news is there are medications to treat parasomnia.

Extremely complex activities, such as cooking a meal, have been documented during sleep. Rare and dramatic examples, brought to light because of criminal proceedings, include acts of murder or rape committed by people who were asleep.

In these cases, the accused persons were diagnosed with parasomnia. And because the offences occurred while they were asleep, their actions were deemed to lack criminal intent and they were found not guilty by the courts.

The second case - dozing off with eyes wide open in the middle of a task such as driving - is known as "microsleep." These are very short naps of a few seconds that occur when your brain drifts off to sleep but your eyes are wide open (like a blank stare) and you continue to perform the activity you were doing.

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Microsleeps - essentially "the lights are on, but no one's home" - generally occur when people are extremely tired and performing a monotonous task such as operating machinery or driving on an isolated road.

Excessive daytime sleepiness is very common, affecting about 1 in 20 of us on a regular basis. However, when driving a vehicle at 100 kilometres an hour, a microsleep of a few seconds is more than enough time to drift across the road into oncoming traffic. Crashes that occur during these brief sleep episodes can be especially deadly because the brakes aren't applied until it's too late, if at all.

Unfortunately, drinking coffee, chewing gum, listening to loud music or turning on the air conditioning won't really stop us from nodding off while driving if we are really sleepy. The best solution is to try to get a good night's sleep before setting out on a road trip. And if you feel sleepy at the wheel, you should pull over where it's safe (such as at a rest stop along the highway) and have a 20-minute nap. Such short naps, also called power naps, are often more refreshing than longer naps.

Dr. Sharon A. Chung is a staff scientist at the Sleep Research Laboratory of the department of psychiatry at Toronto Western Hospital, which is a division of the University Health Network.

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Medical truth or myth? If you'd like a doctor to set the facts straight, send your questions to seriously@globeandmail.com. Be sure to include your hometown and a daytime contact number so we can follow up with any queries.

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Medical truth or myth?

If you'd like a doctor to set the facts straight, send your question to seriously@globeandmail.com. Be sure to include your hometown and a daytime contact number so we can follow up with any queries.

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