I wrote last week answering the question,
how many calories do
our bodies burn during sleep? Contrary
to what many people think, sleep is not an inactive state. During sleep our
bodies are doing lots of important work—repairing cells and tissues, restoring
full, healthy function to our immune system, consolidating memories and
rebooting the neural cells and networks of the brain. We’re burning calories
the whole time. For a 150-pound person, the estimated calorie burn over a 7-hour
night of rest is just over 440 calories. That’s a 40-minute jog on a treadmill!
Getting plenty of high-quality rest is an
important—and still overlooked– factor in weight control. Here are some of the
ways you can harness your sleep routine and your overnight rest to help your
body burn more calories and stay metabolically healthier.
Activate your body’s ‘thinning’ fats
It might surprise you to learn there
isn’t just one type of fat—and certain kinds of fat actually work to burn
energy, rather than storing it. Brown fat and beige fat both appear to have
significant metabolic benefits. In contrast to white fat, these so called
“thinning fats” burn calories, help keep insulin working properly, help regulate blood sugar, and guard
against obesity. Studies in mice
show that animals with higher amounts of brown fat are leaner, and have better metabolic health. Research involving humans has
shown brown fat is linked to lower body mass. On the other hand, a lack of brown fat in mice is
associated with higher insulin resistance, higher blood sugar, and diabetes. Scientists
recently discovered beige fat activates a protein that works to burn calories and generate heat in the body, and may have significant benefits in
combating obesity and metabolic disorders.
What do these metabolically beneficial
fats have to do with sleep? Sleep can contribute to the increase of these
“good” fats in at least a couple of ways. Research has shown that the sleep
hormone melatonin contributes to the increase of both brown fat and beige fat. Regularly getting
enough high-quality sleep, sticking to a consistent sleep-wake cycle, and
protecting daily circadian bio rhythms from disruption are all ways to
encourage your body’s natural melatonin production, which may help your body
make more of these weight-loss promoting fats.
Both brown and beige fat are sensitive to temperature, and can be stimulated by exposure to cool nighttime temperatures.
Research shows sleeping overnight in cool environments increases brown and
beige fat, by triggering the body to convert white
fat to these energy-burning fats. (More on the importance of a cool bedroom for
weight loss in a minute.)
Limit blue light exposure
Blue light aggressively suppresses
melatonin, throws daily bio rhythms out of sync, and inhibits sleep. Research
shows this blue light delays melatonin production for more than twice as long as other light wavelengths, and alters
circadian rhythms by twice the degree.
Where do we get exposure to blue light?
Pretty much everywhere, these days. Sunlight contains blue light. But this
short wavelength light is found in especially high concentrations in digital
screens and energy efficient lighting, including LED and florescent lights. In
today’s world, were exposed to more blue light than ever before, including at
the worst times for sleep and melatonin production—during the evening hours
before bed. A 2017 study found blue light exposure between the hours of 9-11
p.m.—prime time for Netflix, and that evening scroll through social media on
your phone or computer—significantly reduced melatonin production, shortened sleep time, and
led to more restless sleep.
Too much bright light exposure,
particularly in the evenings, compromises our sleep and health—including a
greater potential for weight gain. Blue light’s suppression of melatonin may
inhibit the weight-regulating benefits of this hormone and of sleep itself.
I’ve been acutely concerned about the
blue light problem in our lives for a long time—so I decided to do something
about it. In collaboration with the eyewear company Luminere, I’ve developed a pair of specialized blue-light blocking glasses.
Blue light blocking
glasses are a highly effective, low-cost, easy-to-use protection against the
hazards of blue light—which include a risk of weight gain. Check them out here:
Set an earlier bedtime
Later bedtimes have been linked to
several factors that promote weight gain, including more late-night snacking
and a stronger preference for high-calorie foods. Research has demonstrated a relationship
between going to bed later and gaining weight. What’s behind this connection? There are likely to be several
factors at play. Among them, staying up later simply leaves us with more waking
time to eat, and to be tempted by the most calorie-dense foods (think sugary
sweets and salty fried snacks). Self-control—what we often think of as “willpower”—is a deeply
complicated cognitive process, one that
scientists are still working to understand.
Are we less able to resist ice cream and
cookies and potato chips at night, after a long day of decision-making,
discipline, and focus? Probably so—and studies show that for people who are sleep deprived, cravings for junk food become even
harder to resist. But there’s
little question that removing the temptation is easier than resisting it—and
that’s what an earlier bedtime can do. More time in the evenings sleeping means
less time available for snacking, at the time when many of us are most
With so many of us chronically sleep
deprived, an earlier bedtime also helps ensure that we get enough sleep on a
nightly basis. A single night of insufficient sleep can send hunger hormones
from spiking, sending our appetites on the rise. Being short on
sleep also makes us more prone to stress and for many of us, to emotional
Going to bed earlier isn’t easy for
everyone. In addition to busy schedules and lots of responsibilities that get pushed
to the nighttime hours, some chronotypes are more driven to stay up late than
others. Early-rising Lions and sleep-craving Bears are more likely to welcome
an earlier bedtime than restless Dolphins and late-to-bed, late-to-rise Wolves.
If you’re one of these evening types, don’t give up: even a small, gradual
shift to an earlier bedtime can bring you more sleep, and help keep your
waistline in check.
Don’t know your chronotype? Take my bio time quiz at www.thepowerofwhenquiz.com.
Get light exposure early in the day
Evening light exposure interferes with
melatonin production—and that can make it easier for our bodies put on weight.
But light exposure isn’t all bad for sleep and weight. Far from it. Early in
the day exposure to light helps to strengthen our daily, 24-hour circadian
rhythms, in part by reinforcing the natural decline of melatonin that happens
to us every morning. When melatonin levels drop, you become more alert and
ready to be active. That sends you into your day more energized—and apt to burn
more calories throughout the day.
Morning light also sends powerful cues to
your brain that help keep your daily bio rhythms in sync. These circadian bio
rhythms exert a great deal of control over sleep-wake patterns. Your next
night’s sleep may be the last thing on your mind when you’re just getting your
day underway. But by shoring up circadian rhythms, this early-day light
exposure can have a direct effect on how well you sleep at night—and sleeping
well makes it easier to lose weight and maintain a healthy weight. What’s more,
our bio rhythms do a lot more than control our sleep—they influence nearly
every part of our daily physiology, from metabolism and digestion to hormone
production—including hormones that regulate hunger and fullness.
I just recently gave a TED Talk on the
timing of our hormones, and the best hormonal times to do just about everything, including
eat and sleep. Please check it out!
Sleep in a cool bedroom
Keeping your bedroom cool is one of the
most comfortable, relaxing, sleep-promoting choices you can make for your
nightly sleep environment. A cool bedroom can help you sleep better, able to
fall asleep faster and wake less often throughout the night. A cool nighttime
environment also encourages your body to burn more calories. And, as studies
show, a colder bedroom stimulates the production of beige and brown fats, which
burn energy (aka calories), and help to protect metabolic health.
What’s behind the connection between a
cool bedroom, sound sleep, and weight loss?
Staying cool at night stimulates
your metabolism. Essentially, you need to burn more calories to keep warm.
talked about before, a cool environment is naturally more conducive for sleep. By cool, I’m talking about a bedroom temperature of between 62-68
degrees Fahrenheit, with the optimal temperature being right in the middle, at
about 65 degrees. In the evenings as we move closer to sleep, our bodies
undergo a natural, gradual drop in temperature. (Like so much else going on in
the body, daily thermoregulation, or rise and fall in body temperature, is
regulated by circadian rhythms.) Sleeping
in a cool room can enhance that natural body temperature decline that is part
of our transition to sleep. The fall in body temperature that happens in this
transition to sleep occurs alongside the rise in melatonin that’s both
essential for sleep and helpful to weight control.
Maintaining a cool sleep environment also
has a direct effect on sleep quality and sleep quantity. Warmer nighttime temperatures are linked to more restless sleep with more frequent awakenings throughout the night, and less time
spent in slow wave sleep and REM sleep, two deeply restorative sleep stages.
Sleeping in a cool bedroom will help you fall asleep more easily and sleep more
soundly. Sleeping better gives powerful, fundamental assistance to weight loss.
Cool temperatures also increase the
body’s stores of beige and brown fats, the “thinning” fats that burn calories,
rather than storing them. A 2014 study found that brown fat increased significantly when people were exposed to cool
overnight temperatures. After a month of
sleeping in a 66-degree Fahrenheit nighttime environment, researchers measured
an average 42 percent increase in the participants brown fat, along with an
average 10 percent increase in their fat metabolism. The healthy, young adults
in the study also showed better insulin sensitivity and beneficial changes to
appetite hormones after the month of cool overnights. When scientists had the
study participants return to a warmer nighttime sleep environment, these
weight-promoting benefits diminished or reversed altogether.
Don’t just stop with turning down your
thermostat! Sleeping in the nude is another comfortable way to regulate your
nighttime sleep temperature and sleep more comfortably and soundly, while
burning more calories and increasing your calorie-burning fats.
To help cool down and achieve the ideal
sleep temperature at night, I recommend to my patients the Chilipad, a mattress topper
that helps to regulate body temperature throughout the night, for optimal
temperatures all night long. This sleep system lets bed partners regulate their
temperatures independently of one another. For each sleeper, the pad will lower
temperatures early in the night, to encourage sleep and melatonin rise, and
bring temperatures slightly up near to morning, when a warmer temperature helps
to stimulate alertness.
Eat a sleep-friendly snack
Having an after dinner, pre-bed snack is
a ritual in millions of homes. For sleep and for weight control, it’s important
to keep snacking reasonably light in the evening hours. Research has clearly
shown that the when of eating is really important, and that people who eat a greater share of their daily calories at night are
very likely to throw their circadian rhythms out of sync and gain weight.
But let’s face it—most people will go
looking for a nighttime snack at least occasionally, if not regularly. The goal
is to snack smart. For sleep and weight control, that involves a balance of
protein and complex carbohydrates. Studies—including this 2018 study from
Florida State University—indicate that a protein-rich bedtime snack does not contribute to weight gain, and may have benefits for metabolism and muscle recovery.
I’ve been working with Nightfood to develop an evening treat that won’t interfere with sleep. We’ve
created a sleep-friendly ice cream—yep, ice cream, my personal favorite
nighttime treat. It’s got the right balance of protein and other macronutrients
with the addition of minerals and amino acid that aid sleep. At the same time, it does away with
sleep-disruptive ingredients like caffeine and artificial sugars. It also
tastes great, as I and my whole family can attest. You can check it out here.
With attention to these sleep habits, and
a commitment to making sleep a priority every day, you really can leverage your
sleep to help you lose weight and stay at a healthy weight as you age.
Michael J. Breus, PhD, DABSM
The Sleep Doctor