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Interrupted sleep can prevent slow wave sleep and wreck your mood

If you're a sleep-deprived grump during the day, one solution may be to stay up later, a new study finds.
/ Source: TODAY

Thanks to her job, Savannah Guthrie is obsessed with sleep.

But that doesn’t mean she gets enough of it, especially with two young children and a 4 a.m. weekday wake-up call.

“It is really rare that I fall asleep and stay asleep until my alarm goes off,” the TODAY anchor admitted.

To illustrate just how much of her sleep gets interrupted every night, Savannah was recently monitored during an overnight experiment in a hotel room equipped with the typical distractions from home, including the sounds of a crying baby, a snoring spouse and a phone buzzing with incoming messages.

Dr. Carol Ash, a sleep expert, said that Savannah's Fitbit noted 20 episodes of restlessness during her night. The average Fitbit user is interrupted anywhere from 1 to 30 times a night, she said.

For Savannah, who was given an opportunity to sleep eight hours during her experiment, those interruptions meant she only got the equivalent of four true hours of true shut-eye. The immediate consequences of sleep deprivation can include shortened attention span and impaired critical thinking.

Long term, however, continual sleep problems can lead to weight gain, cardiac trouble and cognitive problems, she said.

Sleep graphic
Are you as restless during the night as Savannah Guthrie was during her sleep experiment? TODAY

If you have sleep-deprived grumpiness during the day, one solution may be to stay up later, according to a study published in Sleep Friday.

People who go to bed later have better moods in the morning than people who go to bed at their regular time, but whose sleep is broken up during the night,

“When sleep is disrupted several times during the night you may never get to slow wave sleep,” explains the study’s lead author, Patrick Finan, an assistant professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine. And that, Finan says, may be what makes all the difference in a person’s mood the next day.

Slow wave sleep is the delicious, deep sleep when our heart rates and breathing slow, our muscles fully relax and our eye movement (REM) is calm. Slow wave sleep is when our bodies truly get rest, regenerate energy and strengthen our immunity. So if you're not getting enough slow wave sleep, your frame of mind is going to suffer, even if you're spending seven or eight hours in bed.

Sleep graphic
The short-term damage from interrupted sleep.TODAY

The Johns Hopkins researchers tried a new experimental procedure to test what happens to people’s moods when sleep only comes in fits and starts during the night: they prodded volunteers awake and kept them from falling back to sleep for 20 minutes out of every hour.

The researchers tested the impact of disrupted sleep on mood with the help of 62 healthy men and women who agreed to spend three nights in a sleep lab. The volunteers were kept up late, but left alone otherwise, were periodically awakened, or were allowed to sleep as they normally would.

Before bedtime and again the next day, the volunteers filled out questionnaires designed to ferret out mood details.

By the second night significant differences emerged between the two groups whose sleep was being tweaked. The group that was regularly nudged awake had a 31 percent reduction in positive emotions, such as feelings of joy, excitement, serenity, and friendliness, as compared to a 12 percent reduction in the group that was kept up late but allowed to sleep undisturbed.

These findings give more insight into the effects of fitful sleep, says sleep expert Peter Franzen, an assistant professor of psychiatry at the University of Pittsburgh School of Medicine, who was not affiliated with the new study.

“There are many, many studies that have looked at the impact of sleep restriction, as opposed to multiple awakenings, which is probably more valid way of looking at insomnia,” Franzen says. “With this kind of model you can begin to tease apart the effects of fragmented sleep.”

Fragmented sleep is different from the kind of insomnia that prevents someone from falling asleep. If you have trouble sleeping through the night, one of the most effective cures is cognitive behavioral therapy.

Franzen suggests these behavioral changes for fragmented sleepers:

Don't stay in bed if you're not sleepy

First, you need to make sure that you are actually sleepy when you are in bed.

“If you wake up and you can’t fall back to sleep in 15 minutes then you need to get up out of bed and stay up until you are tired enough to fall back to sleep,” Franzen says.

Restrict sleep

It may sound counterintuitive that you have to get less sleep to sleep better, but it works, says Franzen.

Figure out how many hours you are actually sleeping during the night and only allow yourself to be in bed for that long, plus a half hour.

“The total time you are spending in bed might be eight hours and you may end up cutting back to six,” he adds. “Soon you’re going to be a pretty sleepy person and you’re going to fall asleep faster and sleep more deeply."

Stick to your wake-up time, no matter what

When you go to bed isn’t as important as getting up the same time every morning.

“Often when someone has a particularly bad night, they want to get up later,” Finan says. “So if they’re supposed to wake up at 6, they’ll want to hit the snooze button and stay in bed till 6:30 or 7. But that just maintains the cycle. You want to set a wake-up time and adhere to that.”