Original subtitles

Alcohol and caffeine can impact our sleep in some surprising ways.

Let's take caffeine to begin with.

Caffeine is a stimulant, and we all know that caffeine alerts us and makes us

feel more awake.

It's in a class of drugs that we actually call the psychoactive

Even though we all know that caffeine wakes us up and makes us more alert,

are at least two other features of caffeine that you may be less familiar

The first of those is the timing of caffeine, and specifically its duration

action. Caffeine has a half -life of about five to six hours for the average

adult. What that means is that about...

50 % of that caffeine is still circulating in your system five to six

after you had that cup of coffee.

What that also means, however, is that caffeine has a quarter life of somewhere

between 10 to 12 hours.

So in other words, if you have a cup of coffee at, let's say, 2 p .m. in the

afternoon, a quarter of that caffeine can still be circulating in your brain

midnight.

So having a cup of coffee in the afternoon may be the equivalent of

yourself into bed at midnight and just before you do, you swig a quarter of a

cup of coffee and you hope for a good night of sleep.

And that's unlikely to happen for some of us.

The second hidden feature of caffeine is its disruption in terms of our sleep

quality.

Now, some people will tell me, look, I'm one of those individuals, I can have an

espresso with dinner and I fall asleep just fine and I stay asleep. I don't

a problem with caffeine.

But even if that's true, it turns out that caffeine can decrease the amount of

deep sleep that you have, stages three and four of non -REM sleep.

And so as a consequence, you wake up the next morning and you don't feel as

restored by your sleep. You don't feel refreshed.

But you don't remember struggling to fall asleep and you don't remember

up at night. So you don't connect the dots. You don't connect the two. But now

you find yourself reaching for maybe two or three cups of coffee the next

morning to feel wide awake because of what we call unrestorative sleep.

I should note, by the way, that there's a huge amount of variability in our

sensitivity to caffeine. And in fact, we know why.

Because there are specific enzymes that are determined by specific genes that we

know of, which will speed up or slow down the metabolism.

of caffeine. And that's why some people will say, I am very sensitive to

caffeine. I just need one cup of caffeine in the morning and that's me.

Otherwise I get the jitters and it's too much. Other people can drink caffeine

maybe up to midday and they're just fine. The way in which caffeine works

back to something we've spoken about previously, which is adenosine and sleep

pressure. And so we mentioned that adenosine builds throughout the day, and

more that we're awake, the more adenosine builds up, and the sleepier

feel. Now, you may have noticed that those two words, caffeine and adenosine,

sound a little bit similar, and they are similar chemically, but they do very

different things.

Caffeine will race into your brain, and it will latch on to the welcome sites of

adenosine, what we call the adenosine receptors in the brain.

And when caffeine latches on to those adenosine receptors, it essentially

hijacks those receptors and it blocks them.

And so as a consequence, caffeine is preventing the signal of adenosine

your brain that you are sleepy, that you've had all of this sleepiness being

built up throughout the day.

So think of caffeine as racing into your brain and essentially hitting the mute

button on adenosine.

And it's fooled your brain into thinking, no, you haven't been awake for

hours. You've maybe only been awake for 4 hours or just 5 hours.

And so your brain doesn't receive the normal signal of sleepiness anymore.

But there's a nasty sting in the tale of this story of caffeine and adenosine.

As that caffeine is in your system and blocking the receptors, that adenosine

still building up.

So if you're burning the midnight oil, you're trying to write a paper late into

the evening or do a work project, and you're sort of drinking those cups of

coffee, then once that caffeine starts to become metabolized and is washed out

of the system, as it were, not only will you go back to the same level of

sleepiness that you were suffering before you had the cup of coffee, you're

going to have that plus

all of the additional denosine that has been building up while the caffeine has

been in your system.

What does this feel like? Well, what it feels like is a caffeine crash because

the caffeine finally washes out of the system and then you're hit with this

wave of sleepiness. And now you have to have an even stronger cup of coffee to

get over that sleepiness signal that has hit you as a consequence.

Caffeine, by way of its impairment or its reduction in deep sleep, could have

significant implications.

We know that it's during deep sleep that we get benefits for the cardiovascular

system and that deep sleep can help prime and recharge our immune system.

And also we know that it's during deep sleep that we cement those new facts

the neural architecture of the brain and making them less likely to be

forgotten. And so therefore, if we're decreasing the amount of deep sleep that

we're getting, we run the risk of not receiving the full benefit from all of

deep sleep that we could naturally be generating, but that we are compromised

because we still have too much caffeine in our system.

Caffeine is sometimes found in hidden places.

I'm someone who typically doesn't drink caffeine. I'm not simply trying to be

the poster child for good sleep. It's just that I'm somewhat sensitive to

caffeine. So I drink decaffeinated coffee sometimes in the morning, but I

get an alerting benefit.

And that's in part because decaffeinated coffee is not non -caffeinated coffee.

Decaffeinated coffee... still has caffeine in it. Now, often it's usually

small amounts, maybe somewhere up to 5 % of the normal amount of caffeine that's

in a standard cup of coffee. But other decaffeinated coffees can actually have

more than that. Some have been found to have 20 or 30 % of the standard amount

of a cup of coffee. So if you have three or four of those, it's the equivalent

of having a full coffee.

Many energy drinks out there have caffeine in them. And of course, they're

designed to wake you up and keep you alert.

Caffeine can also be found in things that we usually have for desserts.

For example, ice cream can sometimes have caffeine in if you look on the

Many of us, as an evening treat, will have a little scoop of ice cream or

have a couple of pieces of dark chocolate. What we may not realize is

couple of segments of dark chocolate can have almost as much caffeine as a cup

of coffee. If you are finding yourself to be struggling with sleep at night,

having a hard time falling asleep or staying asleep, be mindful of your

intake throughout the day, but also just be mindful of the other foods that

you're eating.

Do an experiment.

For the next three days when you're eating and drinking the typical things

you do, try to, as a homework assignment, just turn over the packet

you can look to see if it says caffeine. Or just do a little bit of research and

find out if some of those foods have caffeine in them. And that will help you

best moderate.

Many of us, of course, like to have just perhaps one nightcap in the evening,

just one little tipple of maybe a whiskey or a glass of wine. How bad is

glass or one serving of alcohol?

Well, I would love to say that it doesn't have an impact, but there are

scientific studies demonstrating that even one glass of alcohol in the evening

will end up resulting in measurable changes in your sleep.

Alcohol is perhaps the most misunderstood sleep aid that there is

fact, alcohol is not helpful for our sleep. It's actually quite harmful for

sleep. First, alcohol is in a class of drugs that we call the sedatives.

And sedation is not sleep.

But when you have a couple of drinks in the evening, you mistake the former for

the latter.

You think that you are falling asleep quicker, but really what you're doing is

just simply drifting into a light sedation more quickly. You're not going

naturalistic sleep.

Indeed, if I were to show you the patterns of your electrical brain

when you have normal natural sleep versus your sleep when you've had some

alcohol, a couple of drinks in the evening, you would see that they're

different. It's not the same electrical natural pattern of brain activity.

The second problem with alcohol is that it will disrupt your sleep and you will

wake up many more times throughout the night.

It's what we call sleep fragmentation, and it leads to poor quality of sleep.

Now, the issue here is that these awakenings that alcohol will trigger are

very brief, and so you don't commit them to memory.

So you wake up the next day and you don't feel great, you don't feel

particularly restored, you don't feel very alert, but you don't remember

up as many times as you did throughout the night triggered by the alcohol.

And the way that this works is that alcohol at night can actually shift you

into a more activated state of the nervous system in the body called the

or flight branch of the nervous system.

Alcohol can also trigger stimulating neurochemicals in the brain, and those

things will more likely trigger these awakenings throughout the night, and

that's why your sleep becomes fragmented. The third problem with

it will disrupt your REM sleep.

We know that REM sleep is critical for lots of different functions.

Things such as your mental and your emotional health, such as creativity.

REM sleep and the duration of your REM sleep has even been associated with

duration of your lifespan.

Those people who have more REM sleep on average typically live longer.

Science has some evidence that really speaks to the impact of particularly

alcohol on the disruption of REM sleep.

And in one study, they took a group of adults and they taught them a learning

and memory task where they had to integrate and connect information

And then seven days later, they tested them to see how much of that information

they had retained.

Now, one group learned on the first day and then they were tested out on day

seven. And they had...

Six nights of intervening natural sleep.

A second group did exactly the same thing. They learned without any alcohol

their system. And then they were tested out on day seven without any alcohol.

But just before they went to bed on the first night after learning, they got

them a little bit drunk. They gave them a couple of shots of vodka.

And then they tested them one week later. And then they took a... third

and they did exactly the same thing, but now instead of giving them alcohol the

first night after learning, they gave them alcohol on the third night after

learning. What they found was stunning.

Relative to the group that was getting natural sleep across that one week,

individuals who had their sleep dosed with alcohol and as a consequence had

their REM sleep disrupted either on the first night after learning or even on

the third night after learning, they lost anywhere between 30 to 50 %

of the information that they'd originally learned.

And that tells us how critical sleep after learning is for connecting and

holding on to these memories. And that after the first night of sleep, your

brain is not finished.

With that information processing, it still needs subsequent nights of sleep

good, healthy quality of sleep to lock those memories into place.

Sometimes people will tell me, I don't quite understand it. At the weekend,

have a couple of drinks in the evening.

Maybe I sleep in a little bit late, but I end up having these really strange,

bizarre, odd dreams. They're really intense.

Why is that?

Well, it turns out that your brain is actually quite smart and it understands

how much REM sleep it should normally be getting.

Now, when you have a couple of drinks in the evening, the brain, as we've

mentioned, will be deprived and starved of that REM sleep.

But if you've had perhaps alcohol where finally in the late morning hours, your

liver and your kidneys are starting to get rid of that alcohol.

In those late morning hours, not only do you go on to get the REM sleep that you

normally would have had, but your brain tries to get back some of the REM sleep

that it's been missing because of the blockade of REM sleep by way of alcohol.

And it's what we call a REM sleep rebound effect. You can't get back all

REM sleep that you lost.

The brain is keeping a clock counter of how much REM sleep it should have had,

how much REM sleep it has not had, and how much REM sleep it still needs to try

and get.

Even though it has that system, it's never capable of regaining back all of

lost REM sleep. So you will remain REM sleep deficient as a consequence.

I think the best piece of advice is try to limit caffeine in the afternoon and

in the evenings. Try to stay away from caffeine once midday has happened or

certainly try to stay away from caffeine after 2 p .m. Now, I'm not suggesting

here that you need to stay away from caffeine entirely.

Caffeine does have some health benefits.

But here, it's not just the dose that makes the poison, it's the dose and the

timing that makes the poison. Try to limit yourself to just a couple of cups

coffee during the morning hours and then try to cut yourself off in the

afternoon. If you end up having a couple of drinks at night, it's still good to

maintain your good sleep habits. And that includes regularity. So still

to wake up at the same time of day that you normally would, even if it's the

weekend. Regularity is one of the best weapons that we have in the toolbox of

better sleep.

Because regularity helps keep you on that standard 24 -hour cycle, that

behavior.

the same time, going to bed at the same time, no matter what day of the week or

the weekend it is. That will actually help regularize both your circadian

but also help with managing the different stages of sleep.

so that your brain is never in this state of getting dragged forward or back

time at the weekend.

And when you get that consistency within brain and the body, the body can better

manage the sleep quantity of both non -REM and REM sleep.

I just want to sort of offer a note of kindness here. I don't want to be

puritanical about these things.

science about sleep in relation to alcohol and caffeine and so that you,

individual, you can make an informed choice as to how best you would like to

live your life when it comes to prioritizing your sleep health.