How much sleep you need is one of the most common questions patients ask sleep specialist Dr. Rachel Morehouse, Medical Director, Atlantic Sleep Centre, St. John Regional Hospital, New Brunswick.

The answer, she says, depends on who you are. “It’s a very individual question. I can only give parameters; for example, 95 per cent of people your age need this much sleep.”

Genetics can play an important role in the amount of sleep you get, at least in part, and especially if you carry what’s dubbed the ‘short sleeper” gene, known scientifically as DEC2. Researchers have found that people with this mutation need less sleep, and may be ready to face the day with a smile on their face and a swing in their step after only 6 hours of shut –eye.

It also varies by age. Newborns may require up to 18 hours of sleep a day, but as they get older, they’ll need progressively less dream time. Preschoolers may require in the neighbourhood of 11 to 13 hours a night, while school-aged children can manage with an hour or two less than that.

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Teenagers are notorious for sleeping long hours. They typically clock in at around nine hours each night.

People always think they need less sleep than they actually do

Adults should be getting at least seven to eight hours of sleep per night. Seniors probably need the same amount as younger adults, although they often get some of it in the form of afternoon naps, especially after a restless night. “The older we get, the more aches and pains and other medical issues we develop that may make us more prone to wake during the night.” says Dr. Maureen Ceresney, a Sleep Specialist at the University of British Columbia, Vancouver.

These are ballpark figures and there are always exceptions. Everyone knows someone who gets by on just a few hours of sleep a night. The operative phrase here, though, is “get by”, while some people wake up after getting little sleep, their productivity and other areas of their life may suffer, says Morehouse.

They may be putting themselves at risk for any number of mental and physical health problems. A growing body of research shows that getting inadequate sleep over time can affect memory and learning. Lack of sleep may alter hormones and metabolism and have an impact on the immune system that is similar to being under stress. Sleep deprivation has also been linked to a negative impact on heart health.

“Do you really want to just get by?” asks Dr. Morehouse.

People always think they need less sleep than they actually do, notes Dr. Atul Khullar, a psychiatrist, and Medical Director, Northern Alberta Sleep Clinic (MedSleep Edmonton), “They’re usually fooling themselves.”

If you’re sleeping only five hours a night and want to increase your snooze time, a practical way to do that is to add 15 or 20 minutes a night to your sleep schedule, says Dr. Khullar. That’s easier to integrate into your lifestyle than aiming automatically for eight hours. “It can still make a big difference because that’s an extra two hours of sleep a week.”

Sleep needs across the world are generally similar, although lifestyles can be dramatically different. Some Europeans, for example, arise relatively late, sleep in the afternoon (their siesta time), have a very late dinner (sometimes not until midnight) and often don’t go to bed until into the wee hours. But added together, the number of hours of sleep they get is probably comparable to here in North America.

While sleep habits vary somewhat between individuals and cultures, what has really changed dramatically over the years is the overall amount of sleep we get as a society. We’re generally hitting the sack much less than our ancestors did 100 years ago, says Dr. Khullar. You can blame that on the intrusion of technology and our round the clock lifestyle in which lights and noises constantly interrupt our bedtime schedule.

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