Original subtitles

She's had a week of just awful, awful sleep.

She was waking up probably about ten plus times a night.

Are you being naughty?

You don't want to sleep at all.

Getting your baby to sleep through the night

turns out to be a universal human challenge.

You really need to sleep.

A baby sleeping is not just important for its parents' sanity,

it's fundamental for the baby's development.

A newborn baby is spending 16 hours a day sleeping.

That's an extraordinary amount of time to be asleep.

There's a lot of mystery there about what's going on in these babies.

Why are they sleeping so much?

What an exciting day you've had. You've seen everything.

You're tired as well, aren't you, huh?

The brain is absolutely on fire. It is very, very active during sleep.

This is, in some sense, me-time for your brain.

This is the time when your brain lives out its own existence, if you will.

But you're unaware of it.

Which is, for me, absolutely fascinating.

I feel like we are really just

at the tip of the iceberg with sleep science.

We feel better during the day, we think better during the day,

because of something that's happened in the brain during sleep.

I want to understand how does sleep make you better?

We kept sort of saying to everyone,

"Oh, he's sleeping five or six hours at night, it's great."

Time for a nappy change.

There you go.

The last couple of days that's stopped,

so it's been back to every

sort of two and a half, three hours waking up for a feed again.

Putting him down you've got that initial,

"Oh God, please keep your eyes shut."

Yep.

Like clockwork.

Pretty much 2:00 a.m.,

he's awake.

So I'll go in and grab him...

nappy change,

get his bottle ready,

and then give him a feed.

Sleep deprivation is really hard.

No one's used to waking up every two or three hours

and having to deal with a crying baby.

It really affects you mentally as well.

I am not a nice person without sleep.

Yeah.

Their sleep patterns just change so... so quickly.

Got you, Papa!

Uh-oh!

That was me?

That's you.

You were probably...

ten minutes old.

Do you look at all like you?

No.

- You don't think so? - I really don't.

No.

When I was a new parent, I told all my friends,

"I totally got this. I know how to think about babies,

this is gonna be really easy."

Little did I know.

The eyelashes don't look anything like me.

Well,

you have a lot more eyelashes now.

Yeah, but it's still cute.

There we were, new parents.

And then all hell broke loose,

and it was only because I couldn't figure out

how to get my daughter to sleep through the night.

All right, go on.

As a neuroscientist,

it had not occurred to me to actually study sleep.

Should we let him get chased?

But when I was a newborn parent, there's no knowledge

about what is normal and what one should do.

And so I decided to study sleep in infants.

Surely, we could find out how to think about baby sleep

in a scientifically grounded, biologically-based way.

Everyone knows that baby sleep seems erratic early on,

and eventually it becomes regular.

So we wanted to find out when do babies learn to sleep like we do?

Does it develop gradually?

Does it suddenly occur in the ninth month, for example?

Or does everyone have their own rhythm?

The first thing to do was to figure out how to get the data.

We discovered

that there's a whole set of apps that people are using

to log events about their babies.

Most importantly, sleeping.

That for us is a treasure trove.

So we talked to some app developers,

and this collaboration between the app developers and the scientists

became the NYU Baby Sleep Study.

We're going to visit some of the families

who've signed up for the study

and find out how it is that they're actually using this application,

which will give us a sense of how the data are being collected.

The way we're used to collecting data is

in a small number of subjects,

but with absolutely precise and accurate measurements.

In this case, though, we have no control over anything.

We're not even making any of the measurements.

And so we don't know

whether the times are accurate to the minute, or to the hour.

- Hi. - Hello, Sarah.

- Well, come on in. - Nice to meet you.

- Hi Olivia. - Hi.

- I'm Professor Fenton. - Hi.

I'm curious, when do you log the event?

I logged when he woke up at...

one... what was it, 12:40?

But he went back to bed around 2:20 a.m.

Okay. So you're putting in the hours and minutes.

Uh-huh.

How accurate do you think the minutes part is?

So, I think when I wake up and check my phone in the middle of the night

and see he's awake, it's kind of, like, in my brain that, like,

it was 1:47 that my sleep was interrupted. So that...

And I... That matters to me.

- Come on. - All right. Let's get out of your way.

- Awesome. - Okay.

Thank you very much. Appreciate it.

The thing that struck me the most when I got to meet

some of the study participants

is that they were accurate to the minute.

It was clear that

the error was, by assertion, no more than five minutes.

To have minute-precise data,

and to have millions of those data points...

makes you extremely confident as a scientist in coming to conclusions.

Please meet my longtime colleague,

Pascal Wallisch.

Pascal has a long history of working with lots of data

before they were called "big data."

What you're looking at here is a distribution of babies in the study

around the world.

So every dot here represents a baby.

We have logged data from about 1,000 babies,

and they have produced a total of six million events

made up out of about 1.5 million sleep events, 2.5 million eating events,

and 1.5 million diaper change events.

Collectively.

If you have a large number of babies

and they each have their own rhythm,

but there's a common, underlying pattern to that rhythm,

when you sample enough babies, the pattern will emerge.

And we're beginning to answer the first simple question,

when does the sleep pattern emerge?

Hello, baby.

Hey.

Hey.

Hey!

Kiki's the laid-back one.

Yaya's the one that wants all the attention.

If I'm not tired,

I'm just like, "Okay, this is all right."

If I'm tired I'm just like...

Like, I'm starting to get really bad neck pain from falling asleep like this.

Then you'll be looking at the other one, you'll be thinking, "Okay, hurry up,

'cause your sister's gonna wake up."

They have their own time. This is nap time for them.

And then, at night, is when they wake up

and want to play and do whatever they want to do.

Since they were born,

since the first day, it's just been like that.

- Yeah. - They just won't sleep at night.

Just refuse to sleep at night.

It's very, very tiring.

I have to gear myself up for nighttime, a lot.

It's like a marathon almost, isn't it?

Yeah.

Yeah, twins, hey? Who would have thought it?

Fourteen minutes.

The question that we're trying to answer is,

"Will my baby sleep through the night?"

That's really what they want to know, when that will happen.

We have started to analyze the data,

and we see trends.

But to be very clear, this is very early days, okay?

Uh, we are not comfortable to publish this yet.

But what you see here is that at one month,

there's no clear pattern of when the baby's eating or sleeping, okay?

So, basically sleeping and eating at random,

which is very taxing on the parents.

This was in fact the problem.

- Yes. - Right here in graph form.

But then, within about four months...

an initial cycle is emerging.

And by the time you get to eight months,

there's a hint of a pattern.

And then within a year,

this clear pattern emerges.

Babies are sleeping through the night.

They sleep soon after feeding in the morning,

and about five hours later in the early afternoon,

that's the third time in which they very reliably sleep.

If we had a big enough data set,

this would be very simple to turn into a website

where an individual person could come and say,

"Oh, my kid is within the normal limits.

Everything's fine."

Or, "Everything is likely to be fine."

Or, "My kid is outside of the normal limits."

That would be an early sign that you could recognize

maybe there's a reason for concern, or some kind of intervention,

or, at least, you know, close scrutiny.

The really amazing thing

is to recognize

that the transition from no sleep pattern to a sleep pattern

is something that almost all babies do.

And it'll take about a year.

So, yeah, it took about a half an hour,

I'd say, to get them both to sleep,

which is rare.

That does not normally happen.

I can either...

A, have some "breakfast," which is actually lunch now...

um...

or... I can decide to tidy up this whole place.

So sometimes it's like...

you've got to, like, weigh up what's more important,

eating food

or... having a tidier place to live.

This is the tricky part where I dare not even move

until I'm confident he's definitely gone,

and I can actually get him back and in his crib.

Now he's kind of back awake.

That's it.

I've always been a terrible sleeper.

And, you know, there's this old adage that we study the things that we're bad at.

I always wake up in a groggy state.

I never use an alarm clock.

Alarm clocks are terrible,

you know, 'cause it's important to wake up naturally.

Despite my knowing that,

I still manage to get bad night's sleep after bad night's sleep.

Woe is me.

All animals on this planet have a 24-hour cycle

that is tightly linked to the sun.

That's called a circadian rhythm.

So for us humans, you're awake during the day,

and asleep during the night in the brain,

and it is regulated by the master clock

located within a part of the brain called the hypothalamus.

But that's not true for babies.

When I first started getting involved in sleep research,

I started studying baby rats.

What happens with babies,

baby humans, baby rats,

um, is that they cycle very rapidly between sleep and wake.

If you're looking at a baby like this, it's just complete relaxation...

and then all of a sudden...

Boom. Awake.

And you can tell it's awake

because the left arm and the left leg are in the air at the same time.

And then, look at that, it just goes from this...

vroom.

Asleep.

So over the course of 24 hours,

they can have hundreds of cycles between sleep and wake.

And so that's what makes babies different.

So we wanted to know, you know,

why would that be?

So we started out with a very simple experiment.

We put a dye into the brain of a newborn rat

in the master clock region.

And we wanted to know at what age does that part of the brain connect up

with other parts of the brain that are important for sleep and wake?

When these baby rats were born, we have all of this red dye here

where the master clock is...

but when we look closer to the brain stem,

we see nothing.

We see no labeling at all.

There's no... So it's as if the wires connecting

this part of the brain to this part of the brain just, um...

just don't exist yet.

But if we come over here to a week later,

we now see all of this area now is red.

It was black over here, it's now red over here,

and that's an indication that this part of the brain

is now talking to this part of the brain.

And what we found was it's also happening in humans.

If you look at a model brain,

I'm going to pull it apart

to expose the brain stem,

and the sleep/wake cycles are largely regulated in this region down here.

And then, up here in the hypothalamus,

this is where the so-called master clock is located,

and that's going to be governing your circadian rhythm.

And in newborn infants these areas are not talking to each other,

um, either directly or indirectly.

What that means is that those connections

are what's responsible for

giving rise to the circadian rhythm.

Maybe if you're a parent

and you're struggling to deal with the fact that you're sleep deprived

because your baby is not, you know, getting through the night,

you might just think,

"Well, I just have to wait for these connections to form."

Because prior to three to four months,

there's very little you can do

to help babies sleeping throughout the night.

It's just gonna have to wait for the...

for the circadian system to connect them.

Me and Rachel, we're actually going to try and be proactive.

Survive having a toddler and a baby,

- that might be a... - That's easy.

- Sure. - I got all the confidence.

You haven't done anything on your own with both of them,

so you can't give me that.

We'll test me. I'll have them both to myself

- for a whole day. - You wouldn't... No, you could not do it.

Let's put a bet on it.

- You think... - Fifteen pounds?

- Lily how she is at the moment... - Yeah.

...crying, with Willow crying at the same time.

Fifteen pounds.

Fifteen quid? It should be more than that. Fifty.

Shake.

- Say "please." - Please.

What about fish fingers, Lily? Do you want fish fingers?

Good job.

Yeah? No?

Lily...

can I have the torch, please?

Hey.

Shh...

There. Was it too cold before?

Ugh. Lily.

Oh, I know.

Lily.

Lily.

Put them back for Daddy

and I'll get you a lolly.

Hey, are you all right?

- How you getting on? - I'm fine. How are they?

They're about to sleep.

I can hear someone, so I know they're not.

- Have you not given them a bath yet? - No.

I haven't had the opportunity,

- to be honest. - What have you been doing?

Just tidying up mushrooms.

So they're all over the carpet.

- Okay, well, I'll let you get on. - All right, then.

- I'll see you later. - Bye.

Mummy.

Hi, darling.

Now, why aren't you asleep? You've not had a nap today, have you?

No.

Look at Mummy's hair.

Aww, give her a kiss.

Say, "You look nice, Mummy."

Oh, that's nice.

- So... - Why haven't you been like that with me?

How have they been?

- Morning. Morning. - No, not morning time, bedtime.

- I feel like you played a joke on me. - Morning.

Oh, sorry, what?

- Was it hard work? - Yeah, it's bad. Yeah.

So who won the bet then, Adam?

- Morning. - Yeah, you win.

Is that better?

A bit cooler?

Good stretch!

Ah!

Ah...

Ah? Ah...

Amazing. It's like, I'm sure he's waking up there.

Nope.

Nope.

Just constantly watching what he's doing, wondering what he's thinking.

Look, he's giving a good grin there now.

I don't know whether he's dreaming,

maybe he's dreaming now. Maybe that's a big thing.

'Cause he does do these grins when he's asleep.

And then throws his eyes in the back of his head.

We've discussed a lot about whether we think he dreams or not.

But we were sort of saying he doesn't really have any memories or any...

any experiences yet to dream about.

So unless he's just dreaming about being submerged in...

in water and being upside down and...

hearing a heartbeat and being very warm...

When we studied these rats,

I started noticing all of this twitching.

I was using twitching as a sign that the animals were sleeping.

But when you see a behavior like this,

and it's remarkable behavior...

In many animals it looks like a seizure...

you start to wonder, what do these twitches represent?

This is my dog, Katie...

and you can see the vigorous twitching in both of her limbs,

and even some fluttering in the face.

Most people look at this and they think that Katie is,

you know, chasing rabbits in her sleep.

The historical view going back hundreds of years, if not millennia,

is that twitching is just a byproduct of dreams.

And so if you dream about running, your legs will kick a little bit.

That was the dominant view for...

Well, some people still believe it.

And there was this contrast between what I was seeing with my own two eyes

and what I was reading in the scientific literature.

So over time I just kept asking questions about it.

And it evolved into a whole research program that I never anticipated.

So, let's go into the lab.

So here is, uh, the meeting room for the parents.

And you can see our baby subject.

So for these experiments, we're trying to do

very precise measures of twitching,

and we want to know, can we see evidence of brain activity

that's related specifically to the movements

that we're picking up during sleep?

- Okay. - All right.

Here we go.

- Hey. - Okay.

- Oh, good job! - Cover over her eventually.

Here for like five seconds.

Here we go, baby.

All right, here we go.

The experiment is very simple.

Babies come in,

they're fitted with a cap of electrodes that we use to measure EEG activity,

and then we put them in a car seat, basically, and we let them go to sleep.

It's the easiest experiment you can do. I mean...

Welcome to the...

Welcome to the world of baby research.

I'm just going to start recording.

All right.

See the twitch right there?

Yep, there we go.

Huh. The readout is a lot of lines.

This baby's a champion twitcher. Look at this. Look at this lovely twitch.

Oh, yeah. This is fantastic.

Twitch.

Twitch.

Hey, bubby.

We need to get a lot more of this,

and then the real challenge is the analytical side.

What we found was when a baby is twitching, what's happening,

similar to when you watch a submarine movie...

when all the people on the submarine are being asked to be very, very quiet

because they're about to do a sonar test...

that's similar to when these babies are asleep.

There is very little brain activity...

and then when a baby is twitching,

boom.

That is a sonar test.

The captain of the submarine will shoot off one ping only

out into the water.

And that pinging creates an echo

that is allowing you to see what's out there.

In the same way that the brain is kind of trying to figure out,

"What's out there?"

You know, "What do my limbs do?"

"How many muscles do I have?"

"How are they connected to one another?"

And what we think is happening with twitches is that you're mapping your body.

You're learning about the muscles of your body,

you're learning about how those muscles control joints,

you learn about the relationships,

the synergies among the different muscles in your limbs.

A single twitch can produce activity in hundreds,

probably thousands, of neurons.

And that's what we see in the EEG activity

of these human infants.

It is how the baby learns what kind of body that it has.

That, I think, provides

even further evidence that there's something special

about twitches in early development.

And that's guiding us now in the work that we do.

Rich and I have been trying a little bit of sleep training this week.

We've been putting Pascoe down, uh, for sleep

in his nursery for naps during the day.

We're going to attempt to put him down

in the Sleepyhead in his room for a nap.

I've also promised Rich,

if he manages to put him down successfully,

he can go for a bike ride.

Shh...

Shh...

Shh...

Some people are night owls, but I'm very much the opposite.

I'm a lark.

I like to get up early in the morning.

It's the time where I'm very clear-headed,

I can see through my problems really well.

The benefit of a clear good night's sleep

with a fresh morning run...

it's definitely when I think the best.

I feel like I got into studying sleep accidentally.

My research background was in learning.

In about the mid-2000s, I was a postdoc

at UC Berkeley as a neuroscientist.

I remember this study coming out

saying that sleep deprivation in young adults is bad for the memory...

and that sleep itself was doing something good.

That was really novel and somewhat revolutionary.

And because of my background,

I was in a good position to be able to look at that.

But I want to understand

how does sleep make learning and memory better?

Got you! Balloon!

Oh...

Hey!

Some days she won't sleep at all,

and some days she sleeps quite a lot.

She had a ten-minute sleep this morning, and that got interrupted by the doorbell.

She's beyond tired now.

I've just tried to get her to sleep again, and she's just not.

I think she wants to.

Willow's asleep.

You've got to be really quiet.

Yeah.

Her eyes are closed because she's...

Good night.

She's having a little sleep, isn't she?

Aww.

So, come on in, I'll show you around.

We have a waiting room. Hi.

So our families come in, uh, they might...

We meet them and we get them ready to come into the sleep lab.

When we started this project, studying babies,

there wasn't much that had been done in relation to sleep.

They really weren't things that would get to the heart

of how important sleep was for memory.

We know that infants need a couple naps a day,

so in our study, we wanted to find out...

if naps are essential to protecting the memories.

All right.

Come on, big girl!

Ready?

This is where we're gonna play with some toys.

- Fun. - This is gonna be your chair.

I'm gonna pull it closer this way, though.

Are you ready to see my toys?

What do we have?

There we go.

So we devised this experiment starting with nine-month-olds,

and we teach them this task, and...

which for an infant means to show them how to play with toys

that they hadn't seen before.

They are shown eight toys,

and four of those toys we play with in a certain way.

Not the regular action an infant would be expected to take.

Uh-oh.

What is that?

Then we give them back those toys

to see if they remember the actions we performed with the toys.

What do you think? You want to put on this hat?

After the first step in the experiment,

we record brain activity.

That's when the fun begins for me as a neuroscientist

to really understand whether sleep has an impact

on their memory.

After that, we have two scenarios.

In the first scenario,

the babies are kept awake during the time when they would normally be napping.

- All right. - I can do that.

Put this here. All right, so we have our timer.

And we then see if they remember the actions

we performed with the toys.

So here we have our second infant, and this is after his wake period.

What do we do with this?

In the immediate condition he did dump these right out, right?

Mm-hmm.

It looks like he's more taking the objects out one at a time.

It does seem like there may have been a decay in memory here.

Yeah.

When that baby skipped naptime,

he didn't remember any of the objects.

So you can hang out in here.

In the second scenario, we let the babies take their normal nap.

Just cue, signal, call if you need anything.

Okay.

We let them sleep,

and then, when the infant wakes up,

we can see whether they remembered those toys.

All right.

- Let's take that one out. - Welcome back.

We're gonna take that one out.

So this one,

she just had a good solid nap.

What do we do with this?

The action for this is to open the box,

and then take out the object that's in it, yeah.

Uh-oh.

It's consistent with

having a strong memory for that after the nap.

Hi, baby.

As soon as she gets the cymbals,

she's hitting them together.

- Chain link. - Oh, and the chain link.

So the action for this was

to pull the two blue chain links apart and push them together again.

Good.

Ah.

She seems to remember three target objects,

which is pretty impressive, and I guess consistent with what we would expect,

'cause she just had a nice, solid nap

and it seems to have protected those memories.

So what we're seeing in this study

is that the infants are remembering more of those toys,

or what we did with the toys,

if they took a nap versus when they stayed awake during naptime.

And then we get the exciting part of really digging in

and trying to make sense of it.

What was sleep doing to the brain that is so important for memory?

And so these waves here is a recording of just the brain activity,

um, during sleep.

And these bursts you can see stand out from that record.

Those are called "sleep spindles."

They happen simultaneously across the brain,

which provides a good mechanism for the brain to take information

from short-term memory area, called the hippocampus,

and relocate it in the long-term storage, called cortex.

And that simultaneous burst of activity...

is thought to support the idea that the memories could be moved out

from the short-term hippocampus storage

out to the longer-term storage

by simultaneously firing all of these different parts of the brain

at the same time.

But in an infant, their hippocampus is smaller.

So babies need to sleep in multiple sleep bouts,

two naps and that overnight sleep,

because they have to take that information

that's piled up in their short-term storage

and move it to its permanent location more frequently than we do.

These are the kinds of results I get excited about.

It struck me as a scientist, it struck me as a mom.

Naps are important, and we need to value the time

that the infants are spending sleeping.

Yay!

Ha!

It's not only something that is that downtime for a mom to take a break,

but that it's actually serving a function for these infants.

It's when they're laying down those memories

that are the foundation for everything that they go on to do.

- Hello? - We can hear you and see you.

Can you see us?

No, you gotta put your video on.

Hey, there we are.

- Look. Who's that? - Who's that?

Hi there, Mr. Pascoe!

- Hi. - Hello.

Who is that?

- Hello. - Hi.

Are you being a good boy?

Ooh!

Are you still sleeping through the night?

- Yeah. - What do you say?

We can only see the top of his head.

Yeah. He's got a beautiful cranium.

Yeah, the last three weeks, sleeping through till, like, 6:30-7:00.

- You got it. - Oh, wow.

- Which is nice, isn't it? - Fantastic.

- And he's dropped down to... - You're a good boy!

Dropped down to two naps a day.

Oh, little one.

- Look who's up there on the screen. - What are you doing?

Whoa!

Hello, hello.

We might pop him down for a nap, 'cause I think he's reached his limit.

Say "bye-bye."

Bye, beautiful boy.

- Bye-bye, darling. - Bye-bye.

Say goodbye to Pascoe as well.

Hey!

- Yeah. - We miss you.

Time for a nap, all right?

Good boy.

Shh...

Hey, hey!

Here we are, that's a good spot.

Lots of paddling.

Say, "Yum yum yum."

Yum, yum, yum.

The beach is all too much for little Willow,

who has succumbed to a nap.

Now as soon as it gets to about nine o'clock at night,

she just knows it's nighttime.

She's just asleep from then until she wakes up for a feed,

so it could be like six hours that she'll sleep for sometimes.

Hello, Mrs... Oh!

Is that your hat?

Oh!

We just have a natural rhythm to tell her that it is bedtime.

Big girl!

One's upstairs asleep.

This one stays.

You can't take him up to bed without waking him up.

The sea air does it.

Whether you're getting your sleep during your nap

or getting your sleep overnight,

to overall be maintaining your essential sleep need

is really what it's gonna take

to both stay healthy, but also to think clearly.

So sleep continues to be important

for both our cognitive health, but our emotional health, our mood,

um, and really just how we're able to perform during the day,

whether we're infants or adults.

Sleep has been perennially described

as a period of detachment from the environment,

but our work suggests that sleep

is a very dynamic process with all kinds of changes

in neural activity throughout the brain, changes in behavior.

And so sleep is a much more

multi-faceted process than has generally been thought about in the past.

Sleep is designed for the brain

to actually tackle that immensely difficult problem.

To learn about the world.

And so, that's what your baby is doing when it's sleeping.

It's solving one of the hardest problems in the universe.

We should let them sleep.