You know the feeling you get when you learn something new
about a health problem you’ve been trying to reverse?
Maybe high blood pressure, diabetes, or heart disease.
Well, there’s nothing I like better than bringing you the information
that will help you do just that.
Welcome to the Nutrition Facts Podcast.
I’m your host, Dr. Michael Greger.
Today, we discover the health benefits of sleep.
And we start with the connection between the lack of sleep and weight gain.
Population studies have found short sleep duration
has been associated with obesity in both children and adults.
Observational studies can never prove cause-and-effect, though.
Maybe the obesity is leading to sleep loss
instead of the other way around.
Obesity can cause arthritis, acid reflux, and apnea,
all of which can interfere with sleep.
The relationship between obesity and sleep apnea,
where your breathing repeatedly stops and starts
throughout the night, may be explained by increased
tongue fat—fat deposited inside the base of the tongue—
that may contribute to obstructing your airway
when you sleep on your back.
The reverse causation explanation of the link between
obesity and inadequate sleep is bolstered by the finding
that weight loss interventions can improve daytime sleepiness.
Potential confounding factors also abound.
For example, people with lower socioeconomic status
often work less desirable hours such as rotating or overnight shifts,
or may live in noisier neighborhoods
with poorer air quality, more crime.
The link between inadequate sleep and obesity persists
after controlling for these kinds of factors,
but you can’t control for everything.
You can’t know for sure if sleep deprivation leads to weight gain
until you,...put it to the test.
Have people pull an all-nighter and they get hungrier
and choose larger portions.
Randomize people to shave even just a few hours of sleep off every night
and they start eating an average of 677 calories more a day
compared to the normal sleep control group.
Although individual responses vary widely,
anywhere from eating 813 calories less per day
to as many as 1,437 calories more,
on average, studies found sleep deprivation led people to overeat
by about 180 to 560 calories a day.
Restrict people’s sleep and they also start craving unhealthier choices–
more snacks, more foods that are fatty and sugary.
Stick people in a brain scanner after staying awake all night,
or after few nights of four-hour sleep, and their reward pathways
light up brighter in response to high calorie foods.
Sleep deprivation bumps the levels of the chief endocannabinoid
in the body, the natural chemical we synthesize that binds
to the same receptors as the active ingredient in marijuana.
This may help explain the nighttime nibbling.
On the calories outside of the equation, some short sleepers
may take the extra time to exercise;
others will be so sleepy they exercise less.
The extra wakefulness may raise calorie expenditure
up to about 100 calories a day, but if sleep-deprived individuals
are overeating hundreds of calories, over time
sleep deprivation may end up putting the “wide” in wide awake.
With insufficient sleep inadvertently leading to such
higher calorie intake, it’s no surprise that 4 out of 5 studies
involving as few as 2–5 nights of sleep restriction
found an increase in body weight.
In other words, if you sleep less, you may gain more
OK, but here’s where it gets crazy.
Even if you control calorie intake, you still lose more fat
when you get more sleep.
Overweight subjects who normally got between
6.5 to 8.5 hours of sleep a night were randomized to two weeks
of either 8.5 hours of sleep a night or 5.5 hours of sleep
on the same calorie- controlled diet.
Then the groups switched and spent another two weeks
on the opposite regimen.
So they spent a month living in the lab so their diets and sleep
could be totally controlled and monitored.
Just looking at the scales, sleep duration didn’t seem to matter,
during both periods they ate the same number of calories
and lost the same amount of weight,
but most of the weight lost while getting 8.5 hours was fat,
whereas most of the weight lost when only getting 5.5 hours
of sleep a night was lean body mass.
Same diet, but with more sleep they ended up losing more than
twice as much body fat.
So you snooze you lose… fat!
In our next story,
we discover how getting just one more hour of sleep a night
may help with weight control.
I featured a study that found that
curtailing sleep can cut your rate of body fat loss in half,
while exacerbating the loss of lean mass.
To get better insight into what was going on, researchers took fat
and muscle biopsies from people after a night of sleep loss.
In terms of genes that were turned on and off,
molecular signatures were discovered suggesting
muscle breakdown and fat buildup.
That was after an all-nighter, though,
and in the weight-loss study the sleep-restricted groups
ended up getting little more than 5 hours a night.
What about a more realistic scenario like sleeping
just like one hour less a night?
Overweight adults were randomized to 8 weeks
of a calorie restricted diet or the same diet
combined with just 5 days a week of one hour a night less sleep.
The sleep restricted group achieved the one hour a day less sleep
on weekdays but ended up sleeping an hour more on the weekend days.
So overall, they just cut about 3 hours of sleep out of their week.
Would just those few hours a week make any weight loss difference?
On the scale, no, but in the normal sleep group,
80% of the weight loss was fat,
whereas in the group just missing a few hours of sleep a week
it was the opposite— 80% of the loss was lean.
This shows that a few hours of “catch up sleep” on the weekends
is insufficient, and may in fact be contributing to the problem
based on “social jetlag” effect I explored in a previous video.
A comparable study was designed for kids,
but the sleeping periods only lasted a week.
Eight- to eleven-year olds were randomized to either
increase or decrease their time in bed by 1.5 hours per night
for a week and then switch the following week.
They ate an average of 134 calories more on the days they slept less
and gained in that week about half a pound
compared to the sleep-more week.
The question then becomes would sleeping more facilitate weight loss?
When it comes to body fat, can we just, sleep it off?
The benefit of interventional studies is that you can demonstrate
cause and effect, but observational studies can allow you
to more easily track people and their behaviors
over a longer time span.
For example, researchers followed a group of
mostly overweight individuals who started out to averaging
less than six hours of sleep a night for more than five years.
During that time, about half maintained that schedule
but the other half increased their sleep duration up to
seven or eight hours a night and ended up gaining 5 pounds less fat.
A study entitled “Sleeping habits predict the magnitude of fat loss”
(among those cutting calories)
found that every extra hour of sleep
at night was associated with an extra 1-and-a-half pounds
of weight loss over a period of about 3 to 6 months.
That’s not the same as randomizing people to extra sleep, though.
Maybe they were sleeping more because they were exercising more
and that’s the real reason they lost more weight?
Getting people to bump their sleep from about 5.5 hours up to 7
can lead to an overall decrease in appetite within two weeks,
particularly for sugary and salty foods.
A four-week study getting habitually short sleepers to sleep
about an extra hour a night led them to consume about
two fewer spoonful’s worth of sugar a day compared to
the control group but this didn’t translate
into any changes in body composition.
A twelve-week study, on the other hand,
randomizing overweight and obese individuals
to a weight loss intervention with or without a sleep component
found that the sleep group lost weight significantly faster.
A national cross-sectional survey suggested lower obesity rates
among kids in households that regularly ate dinner together
as a family, got adequate sleep, and limited screen times,
and so Harvard researchers decided to try to...
put those behaviors to the test.
A six-month randomized trial to improve household routines
for obesity prevention among young children resulted in a lower BMI.
Normally it’s hard to tease out the effects
of multi-component interventions, but in this case
exhortations to limit overall TV watching didn’t work,
and the families were already eating together 6 days a week
and so that didn’t change much either.
The only thing they were able to get the kids
to significantly alter was their sleep,
and so the improved weight outcomes may be attributed
at least in part to the ¾ hour average increase in nightly sleep.
Overall, most sleep improvement interventions
tended to show improved weight loss.
I was intrigued to look up the one study that didn’t.
The nice thing about systematic reviews
(as opposed to so-called “narrative” reviews)
is that they exhaustively include mention of every study
that meets some prespecified criteria.
This keeps reviewers from cherry-picking,
but it can also lead to the inclusion of some strange studies.
In this case, a randomized controlled trial of didgeridoo playing,
the indigenous Australian wind instrument.
Those randomized to the didgeridoo to improve their sleep quality
did not lose any weight,
but they also failed to improve the quality of their sleep
(or, likely, that of their neighbors).
Did you know that lactucin, the hypnotic component of lettuce,
is a natural dietary remedy for insomnia?
Here’s the story.
There is a perception that time spent asleep is time wasted,
but it is widely recognized that inadequate sleep is associated
with multiple acute and chronic conditions,
and results in the increased risk of death and disease.
Force people to go one week with only six hours of sleep a night,
and you can change expression of more than 700 genes.
The most dire effect may be endothelial dysfunction.
The endothelium is the thin layer of cells that covers the internal surface
of blood vessels and is responsible for allowing our arteries
to relax and dilate back open properly.
Randomize people for about a week to get five rather than seven hours
of sleep, and just that two-hour difference a night resulted
in a significant impairment in artery function.
Okay, but what do these numbers mean? How bad is a week of 5-hour nights?
Sleep deprivation is no joke.
The magnitude of impairment is similar to that reported in people who smoke,
have diabetes, or have coronary artery disease.
No wonder people who sleep less than seven hours a night may experience
a 12% to 35% increased risk of premature death
compared to those who get a full seven hours.
Yet a significant proportion of the population may
routinely get less than that.
Sufficiently long, restful sleep sessions each night
are said to be an indisputable cornerstone of good health.
Okay, so what can we do about it?
Those who have sleep apnea, a common consequence of obesity
that interferes with sleep, benefit from the use of CPAP machines
while they're losing the weight to treat the underlying cause, hopefully.
But what if apnea isn't your problem?
What if you just have trouble falling asleep or staying asleep?
In my book How Not to Diet, I have a whole section on sleep enhancement,
where I go through the Four Rules of Sleep Conditioning
and the Four Rules of Sleep Hygiene.
What if you follow those guidelines but still can't get to sleep?
Any natural dietary remedies? I already have videos on using
kiwifruit to fight insomnia, and tart cherries, too.
Are there any vegetables that might help?
Lactuca sativa is a plant that has been traditionally used
in the treatment of insomnia.
What is this exotic sounding leafy vegetable? Lettuce!
Evidently lettuce extracts have been used from the time of the Roman Empire
as agents with sedative and sleep-inducing properties.
Lettuce actually does have a hypnotic substance in it called lactucin,
which is what makes lettuce taste a little bitter.
But you don't know if it actually works until you put it to the test.
And it works...in toads. But it also works in rodents.
Sleep in both mice and rats is enhanced by romaine lettuce.
They used romaine since it has a higher lactucin content
compared to other lettuces. Okay, but does it work in people?
About 10 years ago, a study was published in which insomnia sufferers
were randomized to receive lettuce seed oil, oil extracted from lettuce seeds.
Within a week, about 70% of those in the lettuce seed oil group
said their insomnia very much or much improved,
compared to only 20% in the placebo control group.
The researchers concluded that lettuce seed oil was found to be a useful,
safe sleeping aid in geriatric patients suffering from sleeping difficulties.
They chose to study older individuals because insomnia affects surprisingly
20 to 40% of older adults at least a few nights a month.
You think that's bad. Sleep disturbances can plague as many
as nearly 8 out of 10 women during pregnancy.
Of course, there's lots of different sleeping pills,
but they may endanger the fetus or mother.
For example, doctors frequently prescribe Ambien for pregnant women
who have trouble sleeping, but Ambien use is associated with a wide range
of adverse pregnancy outcomes
like low birth weight babies, premature birth, and cesarean section.
And the use of valium during pregnancy has been linked
to birth defects including limb deficiencies.
There has to be a better way. What about trying lettuce?
The lettuce oil study had a number of limitations.
For example, it was only single-blind, meaning the researchers knew
who was on the lettuce supplements and who was on placebo,
which could have introduced some bias. But the researchers essentially said,
"Give us a break. Big pharma has billions to spend on research.
No one wants to fund studies on lettuce."
Finally, we got a double-blind, placebo-controlled study,
but this time on a whole food, not just a lettuce seed extract.
Yeah, but how do you come up with a placebo lettuce?
How are you going to hide who gets lettuce and who doesn't?
Well, you can't fit a head of lettuce into a capsule,
but you can fit whole lettuce seeds.
And here we go: a double-blind randomized placebo-controlled trial
on lettuce seeds for pregnancy-related insomnia.
A hundred pregnant women with insomnia were randomized
to receive capsules containing either a quarter teaspoon
of ground lettuce seeds or a placebo for two weeks,
and those on the lettuce seeds saw a significant improvement
in a sleep quality index score
compared to placebo with no reported side effects.
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To see any graphs, charts, graphics, images, or studies mentioned here,
please go to the Nutrition Facts Podcast landing page.
There you’ll find all the detailed information you need –
plus, links to all of the sources we cite for each of these topics.
My last two books are “How to Survive a Pandemic”
and the “How Not to Diet Cookbook”.
Stay tuned for December 5, 2023
for the launch of my new one, How Not to Age.
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