Lack of sleep impairs cognitive ability
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Most Hopkins students accept that they often need to sacrifice sleep for work or fun. And nearly everyone appreciates the effects chronic sleep deprivation can have on physical health and academic performance. But few stop for a moment to ask whether the status quo is acceptable.
"I need to stay up later if I want to have a balanced college life. I don't mind not sleeping if I can have some fun before. And I stay up until I finish [my work], or otherwise I get up at 5 a.m.," said one senior who echoed a common sentiment on campus.
Sleep is a commodity throughout much of America today. Nowhere is this philosophy more evident than on high-pressure college campuses. We take sleep to be a luxury, something to be traded, rain-checked and caught up on at a later date. A popular refrain in the Hut is, "Sleep is for the weak."
What does it mean to live constantly in this sleepless state? Scientists have undertaken a series of studies aimed at discovering how the body and mind are able to adjust to chronic lack of sleep.
Perhaps the most striking finding is that individuals who do not sleep enough generally do not report being as tired as researchers predict they ought to be. After a few days or weeks of insufficient sleep, people redefine their expectations for how much sleep is normal.
A study published in the March 2003 issue of Sleep looked at subjects forced to sleep either four, six or eight hours a night for two consecutive weeks. Researchers compared the subjects' self-reports of how tired they felt with objective measures of fatigue, including performance on a battery of cognitive tests.
Subjects reported feeling tired when their sleep was initially limited at the beginning of the study, but their reports of sleepiness did not increase after the first few days. Nevertheless, the subjects' cognitive performance declined rapidly, even though the subjects themselves were largely unaware of the changes.
The results of this experiment may indicate that the average fatigued individual vastly underestimates the amount of sleep he or she really needs.
Another interesting finding has to do with the type of cognitive processing that goes on in the tired brain. Research reported in the March 2006 issue of the Journal of Sleep Research suggests that fatigued individuals are more likely to be under automatic processing.
Scientists tested sleep-deprived subjects on a task that involved sorting through a list of words and determining whether they had already seen that word earlier in the experiment. The researchers were looking specifically at priming.
Subjects performed the word recognition at a consistent level regardless of how much sleep they had had. But the more sleep-deprived subjects were more likely to succumb to priming.
The results are surprising because they indicate that, even in the absence of gross cognitive deficits related to sleep loss, individuals are still more likely to switch over to less controlled, more automatic mental processing when they have had insufficient sleep.
The final important point about sleep deficits is that they compound over time, often leading to even poorer sleep on subsequent nights.
Students recognize the problems chronic sleep loss can cause, but often feel they can do little to change them. Freshman YungChi Chuang tries to adjust her sleep schedule.
"Most people say it doesn't matter when you go to sleep, just how long you sleep. But I feel better when I get to sleep earlier and wake up earlier. I think the timing is important."
Freshman Didi Khatib pointed out a paradox in the sleepless habits of late-night studiers. "When people stay up late studying and go to class tired the next day, I don't think they do as well as they would have on a full night of sleep. You need to sleep well to do well."