primary dysregulation of IL‑6 production is responsible for a chronic proinflammatory state, which has a negative impact on health status. It is possible that in some diseases,
which are ageing and chronic inflammation related, IL‑6 could exert a pathogenetic role. In other disorders IL‑6 could be the effect of the diseases rather than a causative factor (i.e. in obesity, diabetes, metabolic syndrome); while in others it could exert a double role of cause and effect at the same time (e.g. CVD, dementia). Future studies that evaluate the effects of blocking the IL‑6 signalling in older persons affected by a chronic proinflammatory state, and different patterns of comorbidity may shed light on this question.
IL-6 and sleep In both young and older persons, the secretion of IL‑6 follows a circadian rhythm with two nadirs at approximately 8 am and 9 pm, and two zeniths at approximately 7 pm and 5 am. REm sleep enhances IL‑6 production through the action of catecholamines, but IL‑6 is inhibited by deep sleep (stages 3–4, non‑REm sleep) and by waking (through the action of cortisol). For this reason, it is produced mainly in the second part of the night when REm sleep is greatly expressed, and is inhibited during the first part of the day (under cortisol influence). On the other hand, IL‑6 negatively influences deep sleep and REm sleep (in the first part of the night), while promoting sleep induction and enhancing superficial sleep (stages 1–2, non‑REm sleep), REm sleep (in the second part of the night) and cortisol release. Sleep disorders that are very common
among the population, such as insomnia, restless leg syndrome and obstructive sleep apnoea, may promote ageing, are cofactors in many age‑related diseases, and increase the risk of mortality in a range of conditions. among the diseases advanced by insomnia and other sleep disorders, are reportedly obesity, diabetes, and CVD. Sleep disturbances that characterise the ageing process would also be an important cofactor of cognitive disorders of varying degrees, of immunosenescence and inflammageing. a number of studies have proved that chronic insomnia can promote an increased risk of mortality for cardiovascular diseases (and in women especially).
Sleep and ageing Sleep disorders promote ageing and ageing‑related disease, generating a global psycho‑neuroendocrine‑immune imbalance. Inflammageing, or low‑grade chronic inflammation, is one of the main players of this imbalance that binds sleep disorders to ageing processes and ageing‑related diseases. While acute inflammation is normally tightly controlled, and is a part of the healing process, the low‑grade elevation of inflammatory markers seen in older adults has been associated with a number of chronic conditions of ageing, such as CVD, diabetes, obesity, sarcopoenia, cognitive decline, cancer, and increased mortality.
a number of inflammatory markers,
especially IL‑6, tumour necrosis factor‑alpha (TnF‑α) and C‑reactive protein (CRP), have the most consistent associations with age‑related chronic disease and disability. Their production increases with age, and high blood levels of IL‑6 in particular, checked at 8 am (> 4.18 pg/ml) is considered an important marker of unsuccessful ageing and ageing‑related disease. The exact mechanism for the increase of inflammatory cytokines with age has not been fully understood. Proposed mechanisms include the known increase in total and visceral adiposity with age (fat mass produces approximately the
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