We noticed that during stage 1, 2, or 3 and 4, there wasn't really very much
going on. But during REM sleep, for this cognitive task, those parts of the
brain that were active while the subjects were learning were again active
during REM sleep. It's another kind of demonstration that here is a replay
going on or rehearsal, whatever you want to call it. Certainly more of the same
is going on while the subject is sleeping.
Does that mean that people get better at something that they've done before
they've slept? Can you just describe what's happening?
... Absolutely. Absolutely. In studies where people are simply allowed to sleep
after they do the study, you see this jump in performance that's quite
remarkable, and in skills tasks, as well. There is an increase in performance
that's not just a free gift. But a good night's sleep will get you this jump in
performance that you would have to work very hard during day time to keep up
In the case of the cognitive tasks, one of the things that happens is that the
number of the density of eye movements goes way up. The number of minutes of
REM sleep doesn't necessarily change, but the number of eye movements really
does go up. It can often double. [This shows] that there's a great deal more
intensity -- maybe more work going on, if you want to put it that way.
In animals, you'll often see increases in the number of minutes of REM sleep.
And in other studies [that] people have done in humans, you see an increase in
REM sleep as well. So the task actually seems to induce more REM sleep.
Of course, if it's a task that doesn't involve REM sleep, there'll be no
change. Recently we've also seen some subtle changes in stage 2, if the task
happens to be a skills task. So it's another kind of design. But you can look
at sleep in that way, and you can see these changes that are actually in the
sleep patterns themselves. There's a change in sleep architecture. ...
How important is sleep for learning?
... If you want to make a lot of progress, you simply have to have it. People
vary in terms of how much they need. But if I had the choice between staying up
a few more hours and trying to get the drop on or get ahead of someone who was
going to bed, I wouldn't even bother. Certainly the sleep is more important
than those extra hours sometimes. You have to have it.
Compare consistently getting a good night's sleep to some other things that
parents might do for their children.
After you've got a student who's got reasonably good study habits, and who's
got the important things like enough to eat and all the basics of comfort, I
can't think of anything more valuable that you could get someone to do than
give them the information that a regular schedule of going to bed, and getting
up as opposed to cheating yourself out of another couple of hours to watch a
late night talk show or something. ...
One of your colleagues compared this to students that had good SAT scores,
students who had been to good prep schools, students who had been tutored
extensively. Can you just talk about that kind of comparison?
Yes, I actually remember a conversation with my friend. In fact, he articulated
it best when he simply said that the best predictor of how well someone is
going to do be they at Harvard or wherever is not their SAT scores or anything
else; it's whether or not they get a good night's sleep. And I have to agree
with that. ...
How important is this sleep deficit in our society -- particularly for
In the studies that we've done where we deprived people even of a partial night
of sleep, we saw deficits that go from anywhere from 20 percent to 50 percent.
I can only think that if you do that as a lifestyle -- imagine taking a course
and you've got a friend who goes to bed every night and who never parties, and
there's you. The two of you are going along, and every day he remembers even 20
percent more than you do. At the end of a month, you can add that up. Imagine
how far this person is going to be ahead of you. ...
The special worry with teenagers is that they are learning a tremendous amount.
They're still learning a lot of motor skills, fine motor skills, as well as
learning all sorts of new cognitive procedural material. There's no end to how
much they can learn. They can be overwhelmed with how much they need to learn.
On top of all that, they're still growing.
Since sleep is important for all of those, a young adult would be crazy not to
get some sleep. You need sleep for growth. You need sleep for lots of other
reasons that we probably don't even know about. This isn't the only reason that
that you have stage 2 and REM sleep. But clearly one of the functions is to
consolidate these tasks and accelerate, make it more efficient. Your learning
is much more efficient if you have a good night of sleep -- that's maybe the
best way to describe it. ...
[How do you feel about the teenage pattern of sleeping late on the
Sleeping in is one of the best things that can happen, and I have always argued
that you should leave them alone. If they really feel like sleeping in, they
probably need that sleep. Later on, when they become young adults, that will
probably disappear. But often, when they're learning a great deal and trying to
keep up with their peers and so on, they're often stretching almost to the
limit of what they can do. And sleeping in is one of the best ways they can do
to sort of stay abreast of what's going on. Let them do it. ...
[What is the message that you want to send out to people?]
When you're learning something that is cognitively very difficult and very new,
and you do get a grasp of it, you can do nothing better than go to sleep.
[It's] the only way that you'll make any real progress.
One of the things that students sometimes do, having not opened say their
physics textbook until the night before the exam, will say, "Hmm, I'm going to
have to stay up all night to get this stuff under control." And chances are
they will not get anything under control. They'll go on to the exam, they'll be
tired, they will not have understood enough of it to really pass. This is
something that takes time.
You've got to learn some; you've got to sleep some; you've got to learn some
more; and it builds. There's certain kinds of material that are difficult
enough that you could only do it this way. This is not simple memorization.
This is stuff that requires you [do] some real cognitive work. And if you're
going to learn that material, you're going to have to get some sleep. ...
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