RESUMO
Disordered sleep impairs neurocognitive performance, and is now recognized to cause metabolic ill-health. This review assesses the nascent relationship between insufficient, misaligned, and disrupted sleep with andrological health. High-quality cohort studies show a reduced sperm count in men with sleep disturbances. Well-designed interventional studies show a reduction in testosterone with sleep restriction. Studies of long-term shift workers show no effect of misaligned sleep on mean testosterone concentrations. Men with obstructive sleep apnea (OSA) and more severe hypoxemia have lower testosterone levels, although it is unknown if this relationship is entirely explained by concomitant obesity, or is reversible. Nevertheless, erectile dysfunction, which is common in men with OSA, is clinically improved when OSA is properly treated. Few studies manipulating sleep have been performed in older men, in whom the accumulation of sleep disturbances over decades of life may contribute to age-related illnesses. Improving sleep could ameliorate the development of these disorders.
RESUMO
The central circadian pacemaker (CCP) located in the suprachiasmatic nucleus (SCN) of the hypothalamus drives the 24-hour pattern in cortisol, which functions as the main central synchronizing signal that coordinates peripheral clocks in organs that control whole body metabolism. A superimposed pulsatile pattern of cortisol allows rapid responses that fine tune the body's reaction to changes in the environment. In addition to coordinating metabolic processes to predictable environmental events, cortisol is the main catabolic signal which acts with testosterone, the quintessential male anabolic hormone, to maintain catabolic-anabolic homeostasis in men. Sleep restriction, when sufficiently substantial, increases late afternoon/early evening cortisol, but does not alter 24-hour cortisol; whereas even maximal acute circadian misalignment only slightly delays the cortisol rhythm. Prolonged circadian misalignment decreases overall cortisol exposure. The implications of these regulatory changes on health and disease requires further evaluation.
