Go to the Globe and Mail homepage

Jump to main navigationJump to main content

(Thinkstock)
(Thinkstock)

Is bi-modal sleep as good as eight straight hours? Add to ...

Morning came a bit earlier this Monday, thanks to Daylight Savings Time. That’s another hour to add to the hefty “sleep debt” most Canadians carry around – the difference between the seven to nine hours of sleep doctors recommend and the actual amount that most of us get. According to a recent American study, 30 per cent of people regularly get six or less hours of sleep.

More related to this story

Some of that sleep debt is accrued in the middle of night, when worries about bills, work and the state of the world’s oceans lead to exhaustion the following day. This wee-hour alertness is fraught with anxiety, as we desperately will our bodies to sleep when they’re “supposed” to. But perhaps waking up in the dark isn’t so bad – maybe “bi-modal,” or two-phase sleep, is the way humans are meant to bed down.

Suddenly, the idea of splitting up sleep time into chunks has become a popular topic. Anthropologists have found evidence that bi-modal sleeping was the pre-industrial norm: Without electric light, people went to bed at sunset. They awoke a few hours later to relax, muse on their dreams or have sex. Then they’d drift off again until sunrise. In the 1990s, psychiatrist Thomas Wehr experimented with leaving subjects in darkness for 14 hours at a time, and observed that a two-phase sleep pattern emerged within weeks.

But it was a recent BBC story titled The Myth of the Eight-hour Sleep that had everyone wondering whether wide-open eyes in the middle of the night was okay after all.

The piece landed in the inboxes of insomniacs and sleep doctors everywhere. Sleeping dos and don’ts are always hot topics, from the impact of iPads in bed to banishing a snoring spouse to a different room. Through every debate, eight hours of uninterrupted sleep is held up as the gold standard, but for Toronto writer Ryan Oakley, learning to sleep in phases was the solution to his lifetime of sleep drama.

“I was exhausted throughout school,” says Mr. Oakley, now 33. “By the time I left high school, I slept in two naps, one when I got home from school and another from about 4 a.m. to 7 a.m.” Mr. Oakley has “delayed sleep phase syndrome,” which in his case is genetic (it can also be caused by head trauma). He prefers to call himself a night owl, one who has never been able to sleep for more than six hours at a time.

As an adult, Mr. Oakley’s attempts at forcing himself out of bed in the morning only left him burned out and depressed. Now he embraces his biology. He sleeps between about 1 a.m. and 4 a.m., then gets up to work, heading back to bed between 10 a.m. and 2 p.m. He’s much happier this way. “If day people could imagine doing chores at three to five a.m., they'd understand what midday is like for me,” says Oakley. “Sadly, they seem to think night owls are lazy or have a choice.”

While the bi-modal sleep idea is intriguing, sleep experts cite years of research in areas from depression to driving that show unbroken sleep is best.

“I’m not a historian or an anthropologist,” says Dr. Charles Morin of Laval University in Quebec City, an insomnia researcher who was sent the BBC article by many friends and colleagues. “But among my patients, those who go to bed at 11 p.m. and get up at 6 a.m. are more rested. Those who go to bed at 10 p.m. and get up at 8 a.m. and also report seven hours sleep are much less satisfied.”

Nevertheless, some people just can't get their sleep in one long stretch – for example, new parents and shift workers. Emily Kitts of Douglas, N.B., is both. She’s the mother of a 15-month-old son, and a respiratory therapist who has alternated between night and day shifts for five years. “Even as a shift worker, nothing prepared me for the sleep deprivation with a baby,” says Ms. Kitts. For his first 10 months, her son slept for two hours at most, often only when he was being held.

After a night shift, the 29-year-old will sleep from about 10 a.m. until 2 p.m., and then try to catch another hour before starting work at 8 p.m. She can’t sleep a lot, so she maximizes what she can get. Books and television are banned from the bedroom, where there are blackout blinds, a white noise machine and earplugs.

Ms. Kitts knows that sleep deprivation has caused her to have mood swings and lapses in judgment. She wants to avoid the illnesses and marital issues suffered by some of her colleagues. “It’s almost a badge of glory at work to say, ‘I haven’t slept in three days and I’m still going,’” says Ms. Kitts. Shift workers have notoriously long lists of health problems, which might highlight the downside of phased sleeping.

“Shift workers tend to have short sleep episodes, and they’re at risk for weight gain, insulin resistance and cancer,” says Dr. Ari Shechter of St. Luke’s Roosevelt Hospital in New York. He’s researching whether such health problems are directly linked to sleep patterns, or to the problematic habits people rely on to make night shifts bearable, such as smoking and buying snacks from vending machines.Waking up briefly once or twice a night is normal, and the halfway point of sleep is often when it happens. The culprit could be too many blankets; body temperature is supposed to decline as deep, slow-wave sleep morphs into the lighter, REM stage. Being too warm often disrupts REM sleep and pre-menstrual women are especially vulnerable. During his PhD studies at McGill University, Dr. Shechter found that a spike of progesterone after ovulation can raise body temperature and disturb sleep. This is also an issue during menopause.

Drs. Shechter and Morin both point out that humans no longer have 12 hours to lie around to get just eight hours sleep. “In a modern environment, people are lucky if they have eight hours to spend in bed,” says Dr. Shechter. “To spend three hours of that awake is a major problem.”

Dr. Shechter advises restless patients to wear less clothing to bed. Holding a hot water bottle to the hands and feet can help the rest of the body cool down. Insomnia therapists also try to help patients learn to deal with wee-hour worries – perhaps writing them down, or doing a calming, low-light activity. The goal isn’t to make the middle of the night a time for recreation. Rather, it’s to help people solidify their sleep into one long, restful stretch, which serves most of us best.

Special to the Globe and Mail

Follow us on Twitter: @Globe_Health

In the know

Most popular videos »

Highlights

More from The Globe and Mail

Most popular