Sleep, particularly the stage of slow wave sleep (SWS) plays a major role in immunological memory and innate immunity. With chronic sleep deprivation susceptibility to infection is increased and immune signalling is dysregulated. This dysregulation gives rise to systemic inflammation, driving development of chronic conditions such as cardiovascular disease, cancer and autoimmune disease. Autoimmune diseases are known to flare up after periods of stress or fatigue and occur far more frequently in women than in men. This suggests gender-dependent changes in inflammation, though the underlying mechanisms are not fully understood. A recent study by Bedesovsky et al. of the department of Neurology at Beth Israel Medical Centre sheds some light on this, identifying different inflammatory changes during sleep deprivation in women and men.
24 participants were subjected to a repeated sleep recovery cycle of three days disturbed sleep followed by one day recovery sleep over 19 days in order to model the immune effects of longer-term deprivation and disturbance. On the disturbance nights, sleep onset was delayed, and subjects were frequently awoken, producing highly disrupted sleep cycles. Sleep quality and duration was measured by polysomnography (PSG) and inflammatory markers were identified in saliva and blood samples collected every second day. Levels of IL-6 cytokine, C-reactive protein (CRP), immune cells and stress hormone cortisol were measured and quantified.
Interestingly, SWS activity increased during the available sleep periods in the deprivation nights, but overall depth of sleep was decreased compared with the recovery nights. Unexpectedly, pro-inflammatory markers CRP and IL-6 decreased, rather than increasing with sleep deprivation in the test group as a whole. However, there were significant gender-dependent differences with females showing an anti-inflammatory and males showing a pro-inflammatory response. Female participants also showed higher cortisol levels than men; an immunomodulator hormone known to facilitate autoimmune disease. This finding is significant as extended periods of sleep deprivation or stress can cause cortisol burnout, producing lowered levels of the hormone and permitting episodes of poorly regulated inflammation. Individuals with autoimmune disease have often reported disease onset and flare ups after such periods of stress.
The results of this study establish a causal link between sleep deprivation and immune dysregulation. Experimental sleep deprivation produces increased cortisol and decreased pro-inflammatory markers in women, compared with increased pro-inflammatory markers in men. This could explain the sex-dependent susceptibility to autoimmune disease in women and establishes sufficient sleep as a protective factor against flare-ups.
To read more about this study and gender dependent immune dysregulation in response to sleep deprivation read the original article at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9648610/.
