"Many adults need five hours of sleep or less."

Now, this is a myth.

"Loud snoring is annoying but mostly harmless."

David Rapoport: Loud snoring is actually a sign

that there is a blockage in your throat.

Robbins: "Your brain and body

will adapt to less sleep."

This is a myth.

I'm Dr. Rebecca Robbins.

I'm a postdoctoral research fellow

at the Brigham and Women's Hospital

and Harvard Medical School.

Rapoport: And I'm Dr. David Rapoport.

I'm a professor of medicine

at the Icahn School of Medicine at Mount Sinai,

and I run the research program in sleep.

Robbins: And we're here today to debunk

some of the most common myths about our sleep.

"Watching TV in bed is a

good way to relax before sleep."

Now, this is not something

that we would necessarily recommend.

If you turn the television on and if it's close to you,

that's a source of bright-blue light.

So, bright light is one of the strongest cues

to our circadian rhythm.

It kick-starts our body and our brain

to become awake and alert in the morning.

It's called a zeitgeber,

the strongest input to that circadian,

the awake phase of our rhythm.

Rapoport: "Drinking booze before bed

will improve your sleep."

So, this is a very commonly used tactic

for people who have trouble sleeping,

and they have a drink.

It's a drug.

It's very much like a sleeping pill.

And it is true that it will help you get to sleep,

as long as you don't drink too much.

One or two drinks, perhaps.

What you do, however, is it disrupts the normal sleep.

It suppresses REM sleep,

which is a normal part of your sleep

that comes on a little while after you go to sleep,

typically 30 to 60 minutes later.

And then, when it comes

that the alcohol has gotten out of your system,

then the REM comes back perhaps at the wrong time,

perhaps too strong, and it disrupts things.

And so basically it is not generally recommended

that alcohol be used as a sleeping pill.

"Lying in bed with your eyes closed

is almost as good as sleeping."

I think that one's pretty definitely not correct.

Sleep is a very specific process

that your body goes through.

The most common myth, if you will,

that we got rid of in the scientific field 50 years ago

is that sleep was like, you know, taking your car

and putting it in the garage and turning off the key

and leaving it there,

and then you come back the next morning

and it just is parked.

Sleep is not like that at all.

Sleep is a very active process.

When you go to sleep, you enter one stage.

A little while later, you enter another stage.

It gets progressively deeper.

You then have the REM sleep,

and then you wake up momentarily,

and that whole cycle takes an hour

to an hour and a half, and then it starts again,

and it happens three to five times in a night.

And if you disrupt any of that,

something happens, and the next morning you feel it.

You don't feel rested.

Now, we don't understand how that actually happens

or why that happens, but we do know it does happen.

So when you're lying in bed, none of that is happening.

If your eyes are closed and you're not asleep,

it just doesn't count.

Robbins: Next.

Rapoport: "If you can't sleep, you should stay in bed

and try to fall back asleep."

If you don't fall asleep,

we generally recommend that you not stretch it out

and stress yourself out by just trying.

And there's probably nothing

that can prevent sleep

as well as, "I've gotta go to sleep."

[Robbins laughs] "I've gotta go to sleep."

"I've gotta go to sleep." Robbins: "I need to!"

Rapoport: You can feel your pulse

and your blood pressure going up.

So what we try and do when

we work with somebody

who has this problem with insomnia

is exactly the opposite of that.

We try and tell them, relax, don't worry about it.

Stay in bed for a little while and see what happens.

But don't try to go to sleep, just relax.

And if you can't relax and if you don't go to sleep,

it's probably better to get up

so that you don't associate the bed

with a stressful situation.

Robbins: All right. "Many adults need

five hours of sleep or less."

Now, this is a myth.

We have scores of epidemiological data

and data from the sleep lab to show

that five hours is not enough

for the vast majority of adults.

There may be some individuals

that maybe do OK on six hours,

but much less than that really is a myth.

Now, you might hear people brag about this,

saying, "Oh I get five, I'm just fine."

But by and large, we do see those people

likely making up for lost sleep on the weekends

or in power naps, for instance.

So, for the vast majority of us,

the recommendation really is seven to eight hours.

Rapoport: This is a real problem

that the sleep field has been trying to address,

and that is that not sleeping has been perceived

as a macho thing.

It proves how great you are,

it proves how manly you are in some cases.

Sleeping is actually good,

and you should sort of be proud of the fact

that you sleep to your need.

Robbins: "Your brain and body will adapt to less sleep."

Rapoport: That sounds like yours.

Robbins: No.

This is a myth.

We see that, just like good nutrition

or a great, healthy diet is so important,

we similarly have a diet that we need

our brains and our bodies to be at their best.

Rapoport: There are actual, formal studies

that have tested

how people perform with lack of sleep

and how they think they are performing.

And it turns out that we basically are really lousy

at saying how sleepy we are.

So you know you feel bad

when you haven't had enough sleep,

but you have no idea how bad you are,

and your performance keeps deteriorating

the more you don't sleep

or restrict your sleep over multiple days,

and you think, "Oh, I've settled in.

I have a little headache, and it doesn't really bother me.

I'm doing just great."

And what is actually happening is

you're performing less and less well

on the various things that we can test,

including driving simulators.

You're falling asleep for three or four seconds

continuously, without knowing it.

Robbins: All right. "It doesn't matter

what time of day you sleep."

Rapoport: If you look at our biology,

we have, inside our brain, a clock.

That clock is set to say,

"This is a good time to sleep."

And then at another time it says,

"This is a good time to be out."

Sleep is timed.

It doesn't just happen.

And even if you don't sleep for the whole night,

you'll be more and more sleepy all night long.

But in the morning, you'll get a second wind,

and that's because the clock says, "Up, time to be up."

It doesn't matter that you didn't sleep,

it's time to be up.

As Rebecca said, we've gained an incredible ability

to not abide by that rhythm.

And the problem is that people think

that they can get away with things

that our biology just won't let us do.

Nurses have been most studied for this,

and firefighters and emergency workers

and people who live on ships.

They all pay a price, epidemiologically.

We've shown higher heart disease,

more tendency to gain weight,

and a variety of malfunctions and difficulties

as time goes on.

You can do it, but it's gonna cost you.

Robbins: "Exercising within four hours of bedtime

will disturb your sleep."

Rapoport: What we give as advice is that

about an hour before sleep,

you wanna try and avoid active kind of things,

and exercise certainly is one of them.

On the other hand, there are people who exercise

close to sleep and do very well.

So I don't think we should say, you know,

if you're somebody who

exercises regularly in the evening

and you sleep beautifully

and you feel rested the next morning,

that you should give up exercise,

'cause I think that would be a bad bit of advice.

You'll gain weight,

you'll lose the toning that you've gotten,

so on and so forth.

On the other hand, if you haven't been doing it,

I probably wouldn't start exercising at night.

And if you're having trouble with sleep,

that's one of the first things we look at,

after drugs like caffeine, to try and get rid of.

Robbins: All right. "Remembering your dreams

is a sign of a good night's sleep."

Rapoport: I think that there is a huge variation

in how much people remember their dreams.

Some of it has to do with when you wake up.

If you wake up during REM sleep,

you almost always will remember a dream.

Some of us don't remember anything

at all about our dreams,

and it doesn't seem to harm them.

But it's not a true thing

that just because you don't remember your dreams,

that you're not having good sleep.

What tells you you're having good sleep

is how you feel the next day.

Robbins: Now, if you're waking up with nightmares,

that could be a simple sign

that maybe your bedroom is too hot

and you need to turn down the temperature.

'Cause a hot bedroom environment unfortunately

can create fragmented sleep

and cause you to wake up often from nightmares.

Now, "Eating cheese (or other food) before bed

causes nightmares."

Rapoport: I don't think I'm aware of any particular food

that will do that to everybody,

but it's very clear that being uncomfortable

will precipitate both bad sleep and waking up

and maybe even nightmares.

So, imagine somebody with irritable bowel syndrome

who knows that whenever they eat, whatever,

gluten or some specific food, spicy foods,

it upsets their stomach when they're awake.

Well, guess what?

If they eat it before they go to sleep,

it'll upset their sleep,

and it may show up as a nightmare.

Robbins: "Loud snoring is annoying

but mostly harmless."

Rapoport: Loud snoring is actually a sign

that there is a blockage in your throat.