more than one-third of american adults don't get enough sleep on a regular basis and chances are
you're one of them if you're watching this video there are lots of different sleep disorders that
affect people but there's a very common one that often gets overlooked as many people don't even
realize it affects them why because the effects are subtle and lingers under the radar that's what
makes it the stealthiest sleep vampire of all something called delayed sleep phase disorder
in order to understand how this works let's understand how our sleep is regulated there
are two main processes that regulate our ability to consolidate our sleep what does
it mean to consolidate or sleep essentially it's the ability for us humans to dedicate one block
of our 24 24-hour day just for sleep as opposed to having to break it up into multiple sleep episodes
so think of one block of sleep as a sleep episode for example going to sleep at 9 00 pm and then
waking up at 6 00 am so your sleep is regulated by many things but the two biggest factors are one
your sleep homeostat and two your circadian rhythm let's talk about your sleep homeostat this is your
brain's version of a thermostat but instead for sleep when you're awake the hypothalamus
part of your brain secretes something called orexin which is a chemical that makes you alert
it circulates in your brain during wakefulness and virtually disappears during non-rem sleep also
the accumulation of adenosine in your brain is the main biochemical process
of lulling you to sleep so the longer you're awake the more adenosine accumulates in the brain
and that's what makes you tired once you fall asleep the drive for sleep dissipates
as the night progresses so the further you are along in your sleep episode the drive for sleep
decreases and the further you are into your sleep episode the percentage of time you spend awake
slightly increases for example tossing and turning or perhaps looking at the clock or something so
you spend slightly more time being in the awake phase the closer you are to the end of the sleep
episode now let's look at the other major factor that regulates your sleep your circadian process
which is driven by your circadian pacemaker aka the circadian clock it's located in the
suprachiasmatic nucleus of the hypothalamus right next to the optic chiasm the optic chiasm is the
collection of nerves that senses light from the environment think of these nerves as an extension
of your eyeballs the percentage of time that young healthy people are awake during a scheduled eight
hour sleep episode will vary by the time of day in other words sleeping eight hours during the day
is not the same as sleeping eight hours at night when it comes to circadian rhythm in humans
the peak drive for wakefulness actually occurs very late in the evening around 8 9 10 pm just
before most people's bedtime then the time that the circadian pacemaker sends off the strongest
drive for sleep is actually near dawn just before when most people wake up in the morning
some might say well that doesn't really make sense now does it shouldn't our circadian clock tell us
to be sleepy in the evening and be wakeful in the morning so why does it happen like this the
circadian clock is set up in our brains like this because its purpose is to facilitate our ability
to remain awake for 16 hours because the drive for wakefulness increases as the day progresses
even though we have this other drive that competes against it meaning our sleep homeostat so remember
with the sleep homeostat we build up an increasing drive for sleep as the day progresses but when it
comes to the circadian clock as the day progresses it increases the drive to stay awake and actually
peaks at the end of the day this is why many mammals will have a burst of energy around
sunset in order to prepare for the nighttime hours and we're very similar in that regard if you think
back to the caveman times it's like making sure all of the day's tasks are completed before the
sun goes away but obviously we no longer live in caveman times but this part of our brain
still thinks that we do and this contributes to us having a lot of circadian rhythm sleep disorders
if we use light exposure to stimulate our eyeballs and therefore stimulate our suprachiasmatic
nucleus and shift our circadian clock so that the peak drive for wakefulness occurs during the time
that we're trying to fall asleep like around 11 pm or midnight it becomes very easy to fall into
that habit and in that case we'll have likely difficulty falling asleep at a reasonable hour
and this is what happens with delayed sleep-wake phase disorder when you look at both this
circadian rhythm and the sleep homeostat together their interaction of these two processes helps to
glue the sleep episode together so that we can maintain a consolidated part of sleep different
than most other mammals and that we mostly don't take a little cat naps throughout the day
or the night instead we have this long marathon duration of sleep typically eight hours or so and
then a long marathon of being awake typically 16 hours so our circadian rhythm is driven by
our circadian pacemaker which is located in the suprachiasmatic nucleus in our hypothalamus this
also drives many other physiological processes like core body temperature and melatonin secretion
which peaks during the night hours our intrinsic circadian pacemaker is very close to being on a
24-hour cycle our circadian rhythms are normally synchronized with a 24-hour day by the light dark
cycle but our timing of onset of melatonin release is genetically determined the interval between the
onset of melatonin release to the time of our regular bedtime at night is typically
four or five hours but that time frame depends on the individual based on our genetics so if you
typically go to sleep at 10 pm your pineal gland is starting to secrete melatonin around 5 pm and
after 8 hours of sleep wake up time is around 6 a.m these are the morning types but people have
different genetics some people might not have their melatonin secretion until later than 5 pm
and if you try to go to bed before you have that melatonin circulating in your brain you're
probably not going to be able to fall asleep for the night if we rewind the clock and go
back to a time before we had artificial light like 200 years ago melatonin would have started
rising around sunset in that instance this peak drive for wakefulness that occurs before sunset
would have been happening in the afternoon but now with artificial light we've pushed our circadian
system to later on in the evening which means our melatonin secretion is happening later in
the night so with artificial light the melatonin secretion is being shifted to later at night and
some people most of them unaware of this have something called delayed sleep phase syndrome
dsps which is also known as delayed circadian phase disorder in this condition the timing
of the sleep episode occurs later than desired and is associated with difficulty falling asleep
and difficulty waking up on time so it's no wonder that when they're forced to wake up at an early
time to go to school or to go to work it's no wonder that they experience a lot of daytime
sleepiness and so they're tired all day and then guess what when it's time to go to bed at a decent
hour despite being tired all day they have a hard time falling asleep because the cycle is repeating
itself this is a syndrome or disorder that has been recognized decades ago these people are often
labeled by the early risers as being lazy but of course that's not really what's going on here
this is actually a fairly common problem and they're more likely to have frequent absenteeism
frequent loss of productivity disruption to work or school activities disruption to social
life or leisure activities and disruption to family life or home responsibilities
and that's hardly surprising because they're essentially sleep deprived like all the time
and for good reason so for people who have this condition if you force them to sleep at normal
times for example if you say look just go to bed at 10 pm and wake up at 6 a.m your body will
adjust over time this has actually been looked at in a sleep lab they usually only end up sleeping
about 25 to 30 percent of the night and this reveals the fact that they're really unable to
sleep at this earlier circadian phase even when they're significantly sleep deprived so instead
of fixing the problem forcing them to shift their sleeping hours earlier only worsen the problem the
best way to fix the problem is sort of three-fold one is to adjust their sleep schedule if possible
but that's not always feasible because people have certain school hours or work hours or whatever
the second thing is to avoid artificial light after the sun sets as much as possible and the
third thing is to strategically take supplemental melatonin more and more artificial light is being
used over the recent years even reading from a light emitting device like a phone or an ipad
in the evening hours this results in huge suppression of melatonin release in the
suprachiasmatic nucleus and this effect can take place over days for example if you're spending
hours looking at these devices in the evening and then you do that for five days in a row circadian
rhythms are shifted later at night by about an hour and a half so our exposure to evening light
for many people will shift their circadian rhythm so that they feel very awake at night like 9 p.m
10 p.m 11 p.m and often don't fall asleep before 1 or 2 a.m another thing that can contribute to
this delay in our circadian rhythm is irregularity in the timing of when we sleep and when we wake up
and this is why getting into a regular sleep routine is important for so many people
those who are on irregular sleep schedules tend to have less sleep during the night time hours
and tend to spend more time or more sleep is spent as compensatory daytime sleep meaning they spent
more of their day taking naps compared to those who maintained a more regular sleep schedule
also regular sleepers tend to have a much earlier timing of their onset of melatonin secretion
now just because someone goes to bed routinely at 2 am that doesn't mean they automatically
have delayed sleep wake time disorder half of these people who look like they have delayed
sleep wake phase disorder with a delayed phase of the onset of melatonin secretion
actually have a normal phase but they have something else going on that is driving them to
go to bed later now this could include things like excessive stress or anxiety or any other number of
issues that may come up that causes them to go to bed later so for example this could include
things like playing video games or watching tv or scrolling tick tock until 2 am well if you're not
going to sleep until two or three or four in the morning of course you're gonna be tired if you
have to wake up at six in the morning so people can have a pattern that looks like delayed sleep
awake phase disorder but they may not actually have an underlying circadian rhythm problem
maybe it's excessive stress and anxiety maybe it's insomnia or something else
now we can also have an altered light period that disrupts our ability to maintain normal
synchronization this was first discovered in 1951 so individuals living within the arctic circle may
have differences in the timing of their sleeping and waking at different seasons of the year
it's based on the fact that sunlight in artificial light suppresses melatonin secretion
it is well proven that we actually need to sleep during the dark hours if we want to maximize our
growth as well as maximize the other benefits of restorative sleep now look at this example these
are pre-term newborns in a neonatal intensive care unit now normally they're kept in continuous light
because it's easier for the nurses to monitor them carefully so they're constantly in the
light but in this study researchers covered their eyes for 12 hours at night they did this
for 21 days straight this actually accelerated their body weight gain and allowed them to be
discharged from the hospital sooner they also had better oxygen levels so the timing of our
exposure to the light dark cycle is important for timing of our sleeping and waking in regard to
synchronization of many different circadian rhythms that can have major effects on our
motor development cardiovascular health and more so getting at least seven to eight hours of sleep
during the night time is ideal although the exact ideal time frame for any given person
is going to vary and if you want more on the latest and greatest tips on getting better sleep
and having more energy check out the link i put in the description below and thanks for watching
you