Uh-oh. Add a good night's sleep to gluttony and the list of other deadly sins. Just like overeating, sleeping too long may seem swell at the time, but it might have a nasty way of coming back to bite you.

A well-publicized article in February's Archives of General Psychiatry reported that people who doze eight or more hours a night are more likely to die than the chronically sleep-deprived.

For the slug-a-bed set, the news that sleeping too long could be toxic had to come like an early-morning bucket of ice water. But as with so much in science, the real story may be more complex than headlines that shrilled, "Sleep Less, Live Longer!"

As it turns out, there is little consensus on how much we should sleep. And while the article's author, Dr. Daniel F. Kripke of the University of California, San Diego, cites an earlier report associating mortality with ample snoozing, others in the factious sleep-research community charge that if nature had its way, we'd all be dozing 10 hours a night.

Spring ahead This morning at 2 a.m., clocks "sprang forward" an hour as we ushered in daylight-saving time — meaning you potentially lost an hour of sleep. To make up for that, try sleeping more than usual the next few nights, suggests the National Sleep Foundation. Take a nap in the middle of the afternoon if you need it, but not within a few hours of bedtime (that could disrupt nighttime sleep).

What's a sleepyhead to believe?

Sparking the controversy was an American Cancer Society study of 1.1 million mostly healthy adults that, among other issues, questioned participants about their bedtime habits.

Contrary to long-accepted belief, Kripke's analysis of that data found that those sleeping 6-1/2 to seven hours a night were least likely to die within the six years covered by the study.

Sleep a full eight hours, and your chance of early death rose 13 percent.

Sleep 10 hours a night, and that jumped an alarming 40 percent for women, 34 percent for men. Five hours was safer than eight, and even safer than 10. Only when you got down to four hours a night did the risk level appear to match what was once considered the right amount of sleep.

Stampede of critics

Still, the apprehensive can take some comfort from the stampede of critics who assailed the findings.

Zzzzz tips James B. Maas, a Cornell University professor who wrote "Power Sleep" (Random House, $13), offers the following tips for a healthful night's sleep: Try to even out your sleep habits. Regularity is important. Don't drink any caffeine after 2 p.m. Don't drink any alcohol within three hours of sleep. Give up cigarettes. Tobacco ruins sleep. To make up sleep deficits, go to bed earlier or take "power naps" (no more than 30 minutes) at your "midday dip," when your biorhythms are low. — Detroit News

Senior analyst Howard Fienberg at the Statistical Assessment Service in Washington, D.C., points out that "the study found an association between sleep and mortality. Association does not mean causation."

Kripke concedes that people should sleep for however long it takes to feel alert and rested. He notes that the study never pretended to suggest cause-and-effect. Long sleepers, he says, might have sleep apnea, a condition in which the individual briefly stops breathing many times through the night, or from depression — both of which can shorten lives.

"What is more certain is that the person who feels adequately rested with five or six hours has little to worry about." But just how much are we supposed to sleep?

At Detroit's Henry Ford Health System, researcher Thomas Roth votes for the standard eight hours, which is also endorsed by the National Sleep Foundation. He cites a classic study in which students were forced to spend 14 hours a night in a darkened room.

Initially, some subjects slept more, but they quickly "leveled off at eight hours."

Life before Edison

For his part, Cornell University sleep researcher James Maas wonders whether we weren't initially programmed to conk out for even longer. "Before Thomas Edison turned on the lights," he says, "we were sleeping 10 hours a night as a nation, which is probably pretty much optimal."

"It's one thing to function," he notes, "another to be alert, creative and not have an unintended sleep seizure driving down the freeway." He recommends a little more than nine hours a night for teenagers, and for most adults, 7-1/2 to eight hours.

The most convincing last word comes from the report's author, Kripke:

"I like between eight and 8-1/2 hours a night. I'm not planning to change my own sleep patterns."