We get it. Netflix, Facebook, Instagram and email can all be stellar distractions to keep you from putting your head on a pillow. But there’s good reason to make sleep a top priority (yes, even above The Bachelor).
Research shows that mixing up your bedtime by more than an hour won’t just impact your energy levels, but it could also affect your weight. In fact, a study published in the journal SLEEP last year discovered that bedtime variability had a negative effect on metabolic health.
Called the Study of Women’s Health Across the Nation (SWAN), scientists looked at 338 non-shift working, middle-aged women and their 14-day sleep diary and then gathered follow-up data via another two-week diary approximately five years later. They found that the greater the difference in bedtime and the later they hit the hay, the higher their insulin resistance. Researchers also found a correlation between more time spent in bed (or going to bed earlier than average) and higher BMI, most likely because that meant more sedentary time.
“We had the opportunity to examine normative sleep patterns in relation to metabolic health outcomes,” says study co-author, Briana Milligan, doctoral candidate at the University of Pittsburgh in the bio-health psychology program. “Our hypothesis was that women with very late and/or very irregular sleep schedules would also have poorer metabolic health profiles,” she says. (That means higher BMI and higher insulin resistance levels.) And the results confirmed this.
“Looking closely at the data, we also found that weekday-weekend differences in bedtime were especially important,” says Milligan. Other health experts agree that it’s your overall sleep patterns that matter. “It’s not just about getting consistent bedtimes during the week, it’s consistent bedtime all the time,” says Robert Oexman, DC, director of The Sleep to Live Institute in Mebane, NC.
How Bedtime Affects Your Weight
According to the American Diabetes Association, as of 2012, 29.1 million Americans had diabetes, and approximately 1.4 million Americans receive the diagnosis each year. The SWAN study suggests that irregular sleep schedules may be an important piece of the diabetes puzzle, says Milligan.
As mentioned, the findings from the SWAN study suggest that avoiding a regular sleep schedule increases insulin resistance. This is an important indicator of metabolic health, including diabetes risk, because it means your body isn’t doing a good job of regulating blood sugar.
So how does that affect your waistline? After we consume food, the body breaks it down into sugars, transported by insulin, and converts it into fat tissues and glycogen stores. “The storing of sugar and using of the stored sugar follows a circadian rhythm,” says Milligan. “During the daytime, we’re storing a lot so we can use it for basal metabolic function, and then our brain and body function optimally while we sleep,” she says. When you go to bed late, your body packs the sugar away and eventually, those stores become full and get converted into fat cells, Milligan explains. And by continuously delaying the release of melatonin (a hormone associated with sleep), the body keeps storing sugar rather than using it, says Milligan. Theoretically, this is why poor sleep could be linked to poor metabolic health.
Findings from earlier sleep studies go even further to say that a sleep debt of four hours a night from participants’ regular eight hours resulted in striking changes in glucose tolerance and endocrine function, impacting the body’s hormones and metabolism. Follow-up research to the that study showed that short sleepers experienced hormonal changes that could affect future body weight and impair long-term health. That’s because to keep blood sugar levels normal, the limited sleepers needed to make 30 percent more insulin than the normal sleepers.
What’s more, people who don’t sleep adequately show an increase in appetite and calorie intake, Oexman explains. The level of leptin (the satiety hormone) falls in subjects who are sleep deprived, therefore promoting hunger. “Because the psychological manifestations of fatigue, sleep and hunger are similar, as adults, we sometimes confuse them,” Oexman says.
6 Tips for Sticking to a Consistent Sleep Schedule
To help you set a sleep schedule you’ll actually stick to — and keep you on track — we asked our sleep experts for their best bedtime advice. Read on for more solid zzz’s.
1. Beware of social jet lag.
Oexman says his patients tell him that they sleep in on the weekends to make up for the sleep they didn’t get during the workweek. “Instead of only sleeping six or seven hours during the weekday, now you’re going to go and spend 10 or 11 hours sleeping in on the weekends,” he says. This is called ‘social jet lag,’ which can involve staying up late during the week for social occasions and then getting up early for work, Oexman explains. Or staying up later on the weekends to hang with friends and sleeping in late. Both of these scenarios can throw off your circadian rhythm for the rest of the week and may lead to changes in BMI and insulin resistance.
“It’s important to get very good sleep every night and I emphasize that people should try to get equal sleep every night,” says Abid Malik, MD, Orlando Health, South Seminole Hospital Sleep Disorder Center. Whether that’s seven to nine hours, you should get that every night, so when the weekend comes around, you’re not in a sleep deficit…and you can get up at the same time on the weekends as you do on the weekdays.”
2. Exercise at prime time for sleep.
“People are staying up until 11 p.m., 12 a.m., even 1:00 a.m. to get their workout in at the sacrifice of sleep because it’s good for them, right?” asks Oexman. Turns out, those late night gym sessions could be doing more harm than good. “These late-night exercisers are often fighting to keep weight off,” Oexman says.
While exercise can be great for sleep, you have to time it right. Aim to finish your workout three to four hours before you plan to snag some shut-eye, Oexman suggests. We experience a spike in body temperature post-exercise, but to sleep, we actually need it to drop. “That’s one of the cues for our bodies to go to sleep,” Oexman explains. “[Exercise] is a great way to help you fall asleep and get good sleep,” so long as you break a sweat on the early side.
3. Regulate your caffeine intake.
Always turning to caffeine to keep you awake? You may want to step away from the Starbucks. “It’s this vicious cycle that people succumb to: They don’t get enough sleep at night, so in order to maintain alertness during the day, they chug energy drinks and highly-caffeinated beverages,” Oexman says. “Then when it comes time to go to bed at night, they’re probably not going to sleep as well.”
Caffeine can actually have a half-life of up to 12 hours. So aim to switch to a decaf beverage (or just sip water) by 2 p.m., according to sleep experts. “Even if you don’t think it impacts your ability to fall asleep, it’s probably interfering with sleep quality,” says Oexman.
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4. Taper your meal sizes.
Eating late at night can impact insulin and is associated with higher obesity rates, according to research. Try to get your last meal in a few hours before bedtime. A good goal for your evening routine: If you plan to go to sleep at 11 p.m. and wake up at 7 a.m., finish your workout by 7 p.m. and have a small dinner soon after, suggests Oexman. That should give your body optimal time for digestion, so you get good sleep and your body is able to regulate blood sugar levels.
This is one of the areas Milligan and her research team plans to continue research in, too. “Irregular sleep schedules may also be associated with irregular meal times and may act on metabolic health by increasing calorie consumption during nighttime hours,” says Milligan. “Previous research has also shown that the ability to metabolize glucose is higher early in the day,” she says. Late-night snackers, consider yourselves warned.
5. Have a relaxation routine.
Start preparing for bed 30 minutes to one hour prior to laying down for sleep, suggests Oexman. Two eight-ounce glasses of tart cherry juice have been shown to increase quantity and quality of sleep, so this would be a good time to drink a glass (early afternoon for the first), says Oexman. A hot bath or shower is also a good idea, as well as some light stretching in a dimly lit environment, Oexman suggests.
“If you can’t establish a stable bedtime routine, just make sure you wake up at your regular time the next day,” suggests Milligan. “This can help you stick to a regular bedtime the next night.”
6. Create a dark, quiet space.
Light, and especially sunlight, has the greatest influence on regulating our sleep-wake cycle, says Oexman. “Get as much sunlight as you possibly can get during the day and then, as you approach bedtime, start taking light away,” he says. Of course, many people view artificial light at night via TVs and tablets, which decrease melatonin production, a hormone we need for quality sleep. “That really impacts our circadian rhythm,” says Oexman.
Give yourself at least 45 minutes away from electronics and light devices to prep your body for sleep, suggests Dr. Malik. “This will hopefully stimulate the melatonin to secrete and then you’ll not only be able to fall asleep sooner, but you’ll get better sleep, too,” says Dr. Malik.