Because there is something as important or more important than sleep time to assess whether we are resting properly. And fundamental advice: there must be at least one day when we go to bed and wake up naturally, without an alarm clock or external influences
You may not need 8 hours of rest. Here’s how to find your perfect sleep time
by Gina ParkCNN
With so much to do this festive season, is anyone getting enough sleep?
Most sleep experts advise adults to sleep seven to nine hours a night for good health and emotional well-being (although this changes as people age). And studies warn that sleeping less than seven hours a day can increase the risk of obesity, high blood pressure, heart disease and other problems associated with sleep deprivation.
CNN has also reported on these risks, including how sleeping five hours or less can increase the likelihood of developing chronic diseases.
Tony Cunningham, clinical psychologist and director of the Center for Sleep and Cognition in Boston, USA, says it’s not as simple as getting the “right” number of hours of sleep. In a conversation with CNN, he explains his reasoning.
Sleep quality is as important as sleep time
Many people tend to focus on the number of hours of sleep they are getting, but neglect the quality of their sleep, which can be even more important than the length of time they sleep.
“There are two different things happening in our bodies that dictate the type of sleep we’re getting and the quality of sleep we’re getting, which are our sleep pressure and circadian rhythms,” explains Cunningham, who is also an assistant professor of psychology at Harvard Medical School, USA.
Sleep pressure or sleep drive builds up during the time we are awake and decreases during sleep. It’s what causes us to start feeling tired after being awake for a long period of time.
“It’s like eating,” says Cunningham. “The longer it is since we’ve eaten, the hungrier we are.”
To get a good night’s sleep, you should go to bed when you have built up a lot of sleep pressure.
Our circadian rhythm is our body’s internal clock.
But let’s not let the name fool us. Although external factors, such as light, can affect our circadian rhythm, the pattern our body follows is guided by the brain.
“The circadian rhythm can fluctuate and send signals that promote sleep or signals that promote wakefulness throughout the day,” says Cunningham. “So if we feel a second wind during a night out in the middle of the night and feel less tired, then that’s our circadian rhythm kicking in.”
For better sleep quality, sleep pressure and our circadian rhythm must work together. This means that any sudden changes or an irregular sleep schedule can affect our ability to sleep and reduce sleep quality.
One way to improve sleep quality “is to start waking up at the same time every day, as this can have a little more impact than going to bed at the same time every day — because it’s not always a good idea to go to bed if you’re not already sleepy,” says Cunningham.
When we have a schedule or general sleep routine, our body naturally begins to look for its ideal sleep time.
How many hours of sleep do we need?
There’s nothing wrong with advising people to get an average of seven to nine hours of sleep, but it’s important to remember that this range is the average.
“This doesn’t mean that every person on the planet needs eight hours of sleep,” says Cunningham. “There are people who really only need five or six hours — as if their biology and physiology only allows them to sleep five to six hours under optimal functioning conditions.”
But this goes both ways. “There are also people who need nine, 10, 11 hours of sleep a night.”
To know how much sleep we need, we can do these two things.
“We should keep a consistent bedtime. I suggest it’s a bedtime where we’re pretty confident we’ll be able to fall asleep in no more than 20 to 30 minutes,” explains Cunningham.
Bedtime should be when we feel sleepy, not just tired. If we go to bed and can’t fall asleep within that 20 to 30 minute window, then it’s likely we haven’t built up enough sleep pressure.
If this is the case, it is best to engage in non-exciting activities, such as taking a shower or meditating with the lights off, until we start to feel sleepy.
“Then we have to find a period of time in our lives where we can sleep until we wake up naturally, without an alarm,” says Cunningham.
“Walk around your room, hide the clocks, cover the curtains, use noise machines, put on an eye mask. Anything we can do to be in your room and not be aware of the time, fall asleep and sleep until you wake up.”
Of course, not everyone has the time to do this exercise. But if you’re a student who’s home for the holidays or have taken some time off from work, it could be a worthwhile experiment, especially if you’re worried about how much sleep you’re getting.
“The first few days you’re likely to sleep longer than you normally would. So if you go to bed at midnight, it’s not unusual for people to sleep until 10 or 11 a.m. for the first few days as they recover their sleep pressure.”
After these first days of recovery, we will know that we have found our sleep time “when we wake up for three or four days in a row at approximately the same time, without external signs, without light signals and without alarm clocks”.
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