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Of course we have heard that during stress our immune system is suppressed. This leads me to wonder, does the immune system get suppressed when we are sleeping and why? During both these conditions the body might need to save energy for other biochemical processes, so I wouldn't be surprised that the immune system is suppressed while a person is asleep.

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  • $\begingroup$ @AliceD is this better? $\endgroup$ – TanMath Jul 7 '15 at 0:12
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    $\begingroup$ Nope. 'I' and 'my' should be removed. Importantly, questions should be generalizable and interesting to the community at large. No one can possibly know why your immune system is, or is not suppressed. Again, it is an interesting question, but it needs re-wording. $\endgroup$ – AliceD Jul 7 '15 at 0:17
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    $\begingroup$ @AliceD what about this question?: biology.stackexchange.com/questions/24555/… $\endgroup$ – TanMath Jul 7 '15 at 0:21
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    $\begingroup$ It is a gray area, but that linked question is not a medical issue, it is an observation of a physiological process that is generalizable to something everyone has experienced in their life. Your question is not readily generalizable as you start of with an unsupported personal anecdote that likely not many folks agree upon. $\endgroup$ – AliceD Jul 7 '15 at 0:27
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    $\begingroup$ I don't have the time for a full answer, so I may come back, but generally 'no'. There is a difference between hibernation (a reduction in metabolic rate to survive prolonged periods of fasting) and sleeping. Humans do not hibernate, and when we are asleep the body doesn't try to save energy. Our brains go through REM sleep, which is just as active as waking hours, our organs -- especially dermal and muscle tissues -- amp-up their repair mechanisms while sleeping. Given that prolonged poor and/or lack of sleep significantly lengthens illnesses, the immune system should be very active. $\endgroup$ – MCM Jul 7 '15 at 1:05
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During stress glucocorticoids, which are steroid hormones produced by adrenal glands (such as cortisol and corticosterone), are released into the blood-stream. These hormones have anti-inflammatory effects. You may say that they suppress the immune system.

The circadian rhythm, which controls the sleep-wake cycle, also controls glucocorticoid secretion, thereby reinforcing the sleep-wake responses [1]. Sleep deprivation is a form of stress and it causes an elevation in the levels of glucocorticoids. The effect of sleep deprivation could be replicated by adrenectomy (surgical removal of adrenal glands); there is a transcriptional downregulation of several neuroprotective genes [2]. Via glucocorticoid mediated signalling, sleep deprivation also results in inhibition of adult neurogenesis in the hippocampus [3].

Another study says that cytokine (TNFα and IL6) secretion by immune-system cells, are inherently affected by circadian rhythm via a glucocorticoid independent mechanism [4].

Overall, sleep is inversely correlated with reduced inflammation because both the processes are under the control of the circadian clock. Sleep deprivation, as a form of stress, is also correlated with glucocorticoid secretion. It should be understood that sleep doesn't necessarily inhibit glucocorticoid secretion and it would be incorrect to say that reduced inflammatory effects are because of sleep.

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  • $\begingroup$ So this means that sleep does NOT cause immunosupression? $\endgroup$ – TanMath Jul 8 '15 at 0:11
  • $\begingroup$ @TanMath Yes it is the opposite actually- immune system may be activated during sleep. But I wanted to refrain from saying that. Because such a strong statement cannot be made. $\endgroup$ – WYSIWYG Jul 8 '15 at 4:44

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