Hello, my name is Thomas Roth.
And I'm from the Henry Ford Hospital Sleep Disorders and Research Center.
And today I'm going to talk to you about excessive daytime sleepiness,
as it's referred to in the clinic.
But just daytime sleepiness in general.
And I'm going to talk about what causes us to have excessive sleepiness,
what are the consequences of that, what are the negative consequences of that.
And very importantly how do we measure that?
How do we know what that means and how do we quantify that?
You're going to study it.
But before we do that let me start out by reminding you about the control
of sleeping and wake.
And what you see on this slide is the parts of the brain which are involved
in the arousal centers.
And in order to keep you aroused,
these neurons have to be activated to cause you to be awake and alert.
To the extent that things like the PPT and LDT do not stimulate the brain, or
the Raphe nucleus, the locus coeruleus, the tuberomammillary nucleus
with histamine, lateral hypothalamus with orexin.
So all of these transmit a serotonin, histamine,
are all very much involved in keeping you alert, to the extent that,
that when that doesn't happen you will wind up with sleepiness.
Now the other thing which is very important to understand, or to remember,
on the bottom of the slide, and you had a lecture on scadian rhythms,
is the super casmatic nucleus, or the SCN, has an important role,
not in producing sleep, but in timing it.
So how do these things work together?
So very importantly, if we sort of start with the sleep load, or
the homeostatic process.
When you wake up in the morning you are fully alert, and
as the day goes on you get more ,and more, and more sleepy.
And here you are by 9 o'clock.
And in fact, you would think that that would be our peak of sleepiness,
but in fact, you can see, that most people then start becoming more, and more alert.
And by the time we're going to bed at 11 o'clock this sleepiness peak
is not working.
So, for example, when are we more sleepy 11 o'clock or 9 o'clock?
Actually were more sleepy at nine.
So, what works against that?
And what we can see works against that is this suprachiasmatic nucleus.
This circadian pacemaker, the SCN, puts out an alerting pulse, which goes up, and
up, and up.
And this counteracts the homeostatic sleep drive.
And for those of you, again, who you remember,
this homeostatic sleep drive seems people get into be related to adenosine.
So very, very clearly this adenosine makes you sleepy.
The suprachiasmatic nucleus puts out an alerting pulse, and how you go to sleep,
right around 9 o'clock at night the circadian the pineal gland secrets
melatonin, which shuts off the SCN and the homeostatic process go put you to sleep.
So again, sleep wakes are controlled by two processes, a homeostatic process,
which gives you sleep load.
And the circadian process, which gives you the timing of sleep and wake.
Now that we understand how sleep is controlled,
let me now turn to talk about how to measure sleepiness.