Some professors would have been offended, but not Pamela Thacher. As she noticed a trio of students dozing off during her psychology class at St Lawrence University in New York State, she spied a research opportunity.

"If you've ever stood in front of a class of 20-year-olds and had three of them fall asleep sitting up, you start to think, is it me? So I was trying to strategise: do I wake the students up? I asked one of them (about it), and he said he had stayed up all night. He told me that was how he kept his grades up."

The study Thacher was inspired to undertake as a result of the trio's snores found that the opposite was true. By comparing the sleep patterns and academic records of 111 undergraduates, she found that those who fuelled themselves with caffeine and studied late into the night, or even "pulled all-nighters" (in American campus jargon), had lower grade-point averages than those who got enough sleep.

"Once you start getting less sleep, you are less able to cognitively cope with the demands of college," Thacher says.

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Many students consider staying up all night a rite of passage, she adds. But all-nighters also seem increasingly necessary as universities intensify their demands that students supplement their coursework with community service; prospective employers require them to participate in extracurricular activities and internships; and parents urge them to get part-time jobs to help cover the spiralling cost of tuition fees.

"Most of our culture tells them that they're making the right choice. It's very macho. It's that idea that you're tough, you're better."

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But Thacher's research shows that rather than helping students to complete assignments or to learn material for exams, sacrificing sleep to study can result in delayed reactions, a tendency to make mistakes and lower academic performance overall.

The resulting report, "University Students and the 'All Nighter': Correlates and Patterns of Students' Engagement in a Single Night of Sleep Deprivation", published last month in the journal Behavioral Sleep Medicine, is part of a growing body of research into students and sleep deprivation. Other US universities and faculty have responded by encouraging their students to get more sleep.

Colgate University in New York State last year ran a campaign called "Come to Bed". Camp beds were placed around the campus and tents were pitched indoors for an event attended by 250 students, who were invited to nap in front of virtual crackling fireplaces while listening to sleep-inducing noises including crickets, rain, waves crashing on the seashore and the institution's vice-president and dean, Charlotte Johnson, reading aloud from the children's book Goodnight Moon.

Tufts University in Massachusetts gives its students sleep masks, earplugs, a sleep diary and a better-sleep guide. It and several other higher education institutions including Indiana University, the University of North Carolina and the University of Texas encourage their students to download sleep-inducing white noise and relaxing music from their websites. The Massachusetts Institute of Technology, whose students are infamously nocturnal, asks parents to report signs of sleep abuse such as emails sent in the middle of the night.

And the all-woman Wellesley College, alma mater of US Secretary of State Hillary Clinton, last year ran a campaign to encourage sleep called "Want As? Get Zs". It threw dormitory pyjama parties, gave away wristbands and badges and used catchy slogans brainstormed by members of the faculty, such as "E=MZ squared" ("energy equals more sleep").

One staff member contributed to the campaign by revamping Wellesley's motto - turning "For women who will make a difference in the world" into "For women who will get some sleep".

"The messaging is a counterpoint to all the things that erode our time and sabotage our sleep," says Vanessa Britto, Wellesley's director of health services, who attended the campaign's pyjama parties in her PJs to talk about the importance of sleep.

"And it's such a low-tech thing. You don't have to pay for it. This is something that needs to be attended to. We're educational institutions, and part of teaching people new things is teaching them about who they are and how to be productive people - physically, intellectually, socially."

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Staff are "invested in getting students to sleep because they want (them) to learn their material".

But, Thacher notes, many universities are sending mixed messages - hers included. During final examinations, she found that the library was open 24 hours a day and food was being served until 11pm. Particularly popular was a vast selection of highly caffeinated energy drinks, made available to students in huge quantities.

"'Oh,' I thought, 'this is not what I need them to be doing'," Thacher recalls.

"Although the universities are trying to encourage more sleep, they are also providing ways for students to pull all-nighters or at least stay up until they're jittery and zombie-esque from sleep loss," she says.

Nearly 40 per cent of students surveyed by the American College Health Association said they felt sufficiently rested no more than two days out of seven. The result is not only poor grades, but also heightened stress, headaches, stomach-aches and listlessness.

"One of the top reasons why students come in for counselling is because they're not doing well academically," says Richard Shadick, director of the counselling centre at Pace University in New York and an adjunct professor of psychology. "Among our first questions to them is: how's your sleep?"

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Jane-Anne Jones, co-ordinator of alcohol and drug education at Colgate, shudders at the mention of all that caffeine. "Oh my God, (students consume) those energy drinks, and then they come in (to the health centre) because they're anxious or they can't sleep, and wonder why."

Jones says there are two groups of sleep offenders. First are the overachievers who have always been rewarded for their success, but have never been taught balance.

"What you see is this tremendous 'they gotta' - they gotta finish this and they gotta have this incredible paper. Their standards are so high and the pressure is self-inflicted. They think the only way they can achieve ... is through self-inflicted punishment."

The second group is made up of students who have always achieved good grades without working particularly hard.

"Then they come to college and it sneaks up on them that that paper is due. So they'll start doing all-nighters. But they're not learning material. What they're learning is how to pass. You don't have any mastery of the topic."

Events such as Colgate's Come to Bed are only small steps in the right direction, Jones says. "Did we make a cultural change? Oh gosh, no," she says, relaxing after running a make-your-own-granola study break for 300 students during final examinations the previous day. "But maybe we got one or two people to think, 'I can do this or I can adjust that'."

Students are increasingly recognising the connection between sleep and good academic performance, Britto says.

"They sort of smile sheepishly when you ask them how they're sleeping, but most of them (now) understand that new memory won't get laid down effectively, they won't learn, they'll get sick when their immune system hits a wall and all (these) things can be attributed to lack of sleep."

But some of her counterparts are less certain that the message is getting through.

"This is a difficult thing to solve because, of all the things they do, students don't see it (sleep deprivation) as a problem," says David McBride, director of student health services at Boston University. "They can see, for example, the visible negative effects of alcohol. Lack of sleep is much more subtle."

For two years Boston has tried to encourage its students to get more sleep by issuing healthy sleep handouts and starting awareness campaigns.

"Our efforts are primarily focused on ... awareness-raising," says McBride, who is a physician. "I don't know if the information we put out has had that much of an impact. If you ask students if they are aware that lack of sleep is harmful to your body, a lot say 'yes'. Whether they incorporate that into their behaviour is another question."

Thacher adds that sleep deprivation is a wider social issue.

"We have to change the culture. Some primary and secondary schools in the American Midwest, for example, are pushing back their crack-of-dawn start times and seeing improved attendance and lower dropout rates. It's happening slowly but surely."

Thacher will continue to research the topic, inside and outside the classroom.

"The great thing about this research is that you have a ready population to study. You can see what's happening right in front of you."

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