While night owls may crow about their high IQs, heightened creativity and supposed “night strength," there is at least one disadvantage to the late life: Night owls are more likely to gain weight as they age, according to a new study by researchers at the University of California, Berkeley.
Researcher Lauren Asarnow found that each additional hour participants put off sleep was linked to an increase of 2.1 points on the body mass index scale over a five-year period. Sleeping the same number of hours as early risers didn’t seem to change this relationship, and neither did exercise or the amount of time they spent in front of screens.
"These results highlight adolescent bedtimes, not just total sleep time, as a potential target for weight management during the transition to adulthood,” said Asarnow in a statement.
Sleep scientists already knew that teens who don’t get enough sleep are more likely to be overweight. But Asarnow’s research suggests it’s not just about the length of sleep; it’s about the time they fall asleep, too.
In her study, a sample of 3,342 nationally representative teen participants answered questions about their sleep habits and lifestyle. The study started with a first wave of teens in 1994 and continued through 2009, when the last group hit adulthood.
Those who went to sleep later were more likely to increase their BMI (proportion of weight to height) over time, which leads Asarnow to suspect that teens who sleep earlier will “set their weight on a healthier course as they emerge into adulthood."
There are a few caveats for the findings, above all that teens self-reported their sleep time and duration in a questionnaire, as opposed to using the gold standard of sleep measurements: sleep diaries, motion sensors and “forced desynchrony,” a process in which researchers re-set a person’s circadian rhythms by exposing them to a certain lightness/darkness schedule. Such methods are impractical for large population studies like hers, Asarnow writes, but they should continue to be used in smaller studies to get more accurate measurements.
In addition to the increased BMI, the study also found that the link between sleeping late and weight gain was even stronger if the participant also ate fast food, which suggests that if teens cut back on eating junk, they may not be at as high a risk.
"This does suggest that if you eat fast food and you go to bed late you are even more at risk for weight gain over time,"Asarnow told HuffPost. "Indeed, fast food consumption might be another target for weight gain prevention."
The National Sleep Foundation recommends that teens sleep between eight to ten hours every night, but only about 15 percent of teens report sleeping at least 8.5 hours on weeknights. They need more rest than adults because their bodies are rapidly growing. However, because of the hormonal changes taking place in their body, teens will feel sleepy two hours later than they did as children, pushing their natural bedtimes to 11 p.m. Unfortunately, most high schools in the U.S. start at around 8 a.m., which explains why teens report getting an average of only seven hours of sleep a night.
While Asarnow's research doesn't explain why there's a link between late bed times and weight gain over time, there are a number of possible explanations. Sleep helps people maintain healthy weights because rest helps regulate the hormones that control our appetites. Getting more sleep also means you're energized throughout the day, which ups the chances for exercise. Finally, more sleep can also aid in healthy weight maintenance simply because the hours you spend sleeping are hours you aren't eating.
26 Ways to Sleep Better
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Open Image ModalSharper Memory When you're awake, your brain naturally builds up beta-amyloid (proteins that are a strong biomarker for Alzheimer's disease), but while you sleep, the brain flushes out some of those toxins. According to a recent study, older adults who reported regularly getting adequate rest had fewer beta-amyloid deposits in their brains than those who got less sleep.
Stronger Heart A study of more than 30,000 adults found that those who slept for roughly seven hours were far less likely to develop heart disease than those who averaged only five hours. Skimping on sleep may disrupt your hormones and metabolism, and increase blood pressure and inflammation.
Slimmer Waistline Brain scans in healthy adults reveal that a good night's sleep impacts areas of the brain that regulate your desire for high-calorie foods, according to 2013 research in Nature Communications. When presented with food options, study subjects wanted treats containing an average of 600 fewer calories when they were well rested compared with when they were sleepy.
—Jessica Migala
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Open Image ModalTelling yourself you got a good night's rest may make a difference in how you think and feel: In a study in the Journal of Experimental Psychology, scientists told one group of subjects that they had logged an above-average amount of REM sleep, while a second group was told they didn't get enough. Then everyone was given a test that measured their cognitive function. The above-average sleepers performed better than those told they'd slept poorly. "Simply hearing that you had high-quality sleep may trigger automatic responses, like heightened energy, that your brain has come to associate with being well rested," says study coauthor Kristi Erdal, PhD.
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Open Image ModalBy the time children reach adolescence, they may begin sleeping less—but homework isn't the only culprit. In a recent poll, 16 percent of kids said they woke up to send or read texts and e-mails. Compare your child's sleep habits with the stats:
Age: 6-11Hours of sleep most kids are getting: 9 or more Hours of sleep they need: 10-11
Age: 12-14Hours of sleep most kids are getting: 8 Hours of sleep they need: 9-10
Age: 15-17Hours of sleep most kids are getting: 7 or less Hours of sleep they need: 9-10
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Open Image ModalBefore you hit the sack, cue up a soothing playlist. Research in the International Journal of Nursing Studies found that when insomniacs listened to relaxing music for 45 minutes prior to bedtime, they spent more time in REM sleep.
—Jihan Thompson
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Open Image ModalIn one of the first studies to examine how room temperature impacts people with sleep apnea—a condition that affects an estimated 18 million or more Americans—researchers discovered that when the thermostat was set at 61 degrees instead of 75, subjects slept on average 30 minutes longer and reported feeling significantly more alert the next morning.
—Jihan Thompson
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Open Image ModalExhaustion can be a sign that you're not just sleepy, you may be sick. If nothing helps you feel rested, one of these conditions may be to blame.
Anemia A telltale sign of iron deficiency (the number one nutritional deficiency in the world) is fatigue, caused by a lack of red blood cells. If you're anemic, your doctor may suggest dietary changes, like loading up on iron-rich meats and veggies.
Diabetes When your body is no longer able to effectively convert glucose into energy, you can eventually feel weak and wiped out.
Fibromyalgia More than 75 percent of people who suffer from this disorder, which causes widespread muscle pain, report having trouble sleeping. Why? According to some brain wave studies, the disease may cut off time spent in stages III and IV of sleep, when the most restorative rest occurs.
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