- Hello, I'm Dr. Yvonne Chu.
My background is in internal medicine and sleep medicine.
And today, I'm going to talk to you
about the bidirectional relationship
between sleep and immunity.
We've all experienced it.
When we get sick,
we feel, we may develop a fever,
we feel tired, fatigue, and we wanna sleep a lot.
And it's thought that the role of this sickness behavior
is to conserve energy as our body mounts an immune response
to fight off this pathogen.
When we look at polysomnography tracings,
we see that there's an increase
in non-rapid eye movement sleep or non-REM sleep.
And we also see, at the same time,
that there is a decrease in REM sleep.
Now, in particular, there is an increase
in the slow-wave or stage three sleep during acute illness.
And slow-wave sleep is felt to be
the most restorative of the stages of sleep.
So it makes sense that when we're ill,
the slow-wave sleep is increased.
At the same time, REM sleep is suppressed.
During REM sleep, our bodies are paralyzed.
And as we know, we shiver to produce fever.
So the shivering mechanism is suppressing REM sleep.
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The body gets alerted to the invading pathogen,
and the body then goes on
to mobilize its immune defense mechanisms.
And the whole point is ultimately to isolate
and destroy the pathogen.
So, during this acute phase response,
there's an upregulation in the inflammatory cytokines.
And many of these cytokines have been studied
to be related to sleep,
and in particular, the most studied of these cytokines
are IL-1 beta and TNF-alpha.
Both have been shown to regulate non-REM sleep.
We know that, in sleep-deprived individuals,
IL-1 and TNF are both increased.
Likewise, when we are infected
with, you know, with a pathogen,
these levels are increased as well.
And in response, non-REM sleep is increased
and REM sleep is suppressed.
In some human studies,
giving subjects who are sleep-deprived blockers
for TNF and IL-1 in the form of antibodies
and receptor blockers,
there was a loss of the rebound stage three sleep
that we would normally see
in these sleep-deprived individuals.
We know that in shift workers
who are thought to be chronically sleep-deprived
due to the constants changes in their shifts at work
and also the circadian mismatch that goes along with it,
well, these individuals are shown to have higher incidences
of getting infections compared to non-shift workers.
In another study with healthy volunteers
who were given nasal droplets of rhinovirus,
it's been shown that those who chronically get less
than seven hours of sleep a night
are three times as likely to develop the common cold
compared to those who routinely get eight hours
or more of sleep.
And then there's studies on adaptive immunity
in the form of vaccine studies.
We know that vaccines are effective
when the inoculated antigen results
in an effective antibody titer.
There are some studies that look at, in human subjects,
the effects of sleep loss
on the subsequent antibody titers levels
that form after giving someone a vaccine.
And in particular, have been looked at influenza vaccine,
the hepatitis A vaccine and hepatitis B vaccine.
Subjects would be deprived of sleep
for about four hours a night in the days preceding
getting the vaccine and in the immediate one to two days
following the vaccine.
And it's shown that, later on,
these subjects develop a much,
a significantly lower level of antibody titers compared
to those who are not sleep-deprived.
So there's also this theory that chronic sleep deprivation
results in chronic low-grade inflammation.
And as we discussed earlier,
the cytokines IL-1 and TNF, among other cytokines,
get upregulated in the setting of acute sleep deprivation.
Well, it's thought that,
if we have someone who is chronically sleep-deprived,
they have this chronic elevation in these cytokines.
And we know that chronic inflammation has been associated
with various medical conditions,
such as obesity, diabetes,
coronary artery disease, cancers,
and neurodegenerative disease.
So, the question is,
could chronic sleep deprivation increase our risks
for developing one of these medical conditions?
Well, that's left, you know, to be determined
with further research.
There is no substitute for getting adequate
and good quality of sleep consistently
if we want to get all of the potential immune
and restorative benefits that sleep has to offer.