[Music]
My name is Matthew Walker I am a
professor of neuroscience and psychology
at the University of California Berkeley
and I am the author of the book why we
sleep we certainly know that a lack of
sleep will actually prevent your brain
from being able to initially make new
memories so it's almost as though
without sleep the memory inbox of the
brain shuts down and you can't commit
new experiences to memory so those new
incoming informational emails are just
bounced and you end up feeling as though
you're a music you can't essentially
make and create those new memories we
also know that a lack of sleep will lead
to an increased development of a toxic
protein in the brain that is called beta
amyloid and that is associated with
Alzheimer's disease because it is during
deep sleep at night when a sewage system
within the brain actually kicks into
high gear and it starts to wash away
this toxic protein beta amyloid so if
you're not getting enough sleep each and
every night more of that Alzheimer's
related protein will build up the more
protein that builds up the greater your
risk of going on to develop dementia in
later life what are the effects of sleep
deprivation on the body well there are
many different effects firstly we know
that sleep deprivation affects the
reproductive system we know that men who
are sleeping just five to six hours a
night have a level of testosterone which
is that of someone 10 years their senior
so a lack of sleep will age you by
almost a decade in terms of that aspect
of virility and wellness we also know
that a lack of sleep impacts your immune
system so after just one night of 4 to 5
hours of sleep there is a 70% reduction
in critical anti cancer fighting immune
cells called natural killer cells and
that's the reason that we know that
short sleep duration predicts your
risk for developing numerous forms of
cancer and that list currently includes
cancer of the bowel cancer of the
prostate as well as cancer of the breast
in fact the link between a lack of sleep
and cancer is now so strong that
recently the World Health Organization
decided to classify any form of
nighttime shift work as a probable
carcinogen so in other words jobs that
may induce cancer because of a
disruption of your sleep wake rhythms we
also know that a lack of sleep impacts
your cardiovascular system because it is
during deep sleep at night that you
receive this most wonderful form of
effectively blood pressure medication
your heart rate drops your blood
pressure goes down if you're not getting
sufficient sleep you're not getting that
reboot of the cardiovascular system so
your blood pressure rises you have if
you're getting six hours of sleep or
less a 200% increased risk of having a
fatal heart attack or a stroke in your
lifetime there is a global experiment
that is performed on 1.6 billion people
twice a year and it's called daylight
savings time and we know that in the
spring when we lose one hour of sleep we
see a subsequent 24% increase in heart
attacks the following day another
question perhaps is what is the recycle
rate of a human being how long can we
actually last without sleep before we
start to see declines in your brain
function or even impairments within your
body and the answer seems to be about 16
hours of wakefulness
once you get past 16 hours of being
awake that's when we start to see mental
deterioration and physiological
deterioration in the body we know that
after you've been awake for 19 or 20
hours your mental capacity is so
impaired that you would be as deficient
to someone who is legally drunk behind
the wheel of a car so if you were to ask
me what is the recycle rate of a human
being it does seem to be about 16
and we need about eight hours of sleep
to repair the damage of wakefulness
wakefulness essentially is low-level
brain damaged