Sleep: A Health Imperative

Abstract

contribute to chronic disruption of biological timing as well as increased risk for a number of illnesses.Many people judge their sleep as adequate as long as a minimal level of behavioral functioning can be maintained.With no perceived negative outcome, it is understandable why sleep may be sacrificed for work or pleasure.Indeed, the percentage of men and women reporting sleeping less than 6 hours per night has increased significantly over the last 20 years (Figure 2).7 In contrast to this perception of sleep's limited importance, decades of research clearly indicate that sleep is comprised of complex, active, and highly organized physiological processes, which when disordered or deficient results in ill-health or death. Sleep is Exquisitely Organized and ControlledNight after night sleep is remarkably consistent in its organization.Each night is comprised of recurring, complex, active physiologic processes, confirming that sleep is not a biologically inactive time interspersed between periods of wakefulness.Human sleep (and that of most mammals and birds) is composed of two distinct states: non-rapid eye movement (NREM) and rapid eye movement (REM), each with unique characteristics and each actively regulated by distinct neural centers.A typical night involves 4 to 6 repeated cycles of NREM and REM, each lasting approximately 90 to 110 minutes.NREM sleep is divided into 3 stages (N1, N2, N3) characterized by progressively more synchronous cortical neuron activity, stable autonomic function, and increasing arousal thresholds.In contrast, the electroencephalogram (EEG) during REM sleep shows low-voltage, mixed-frequency brain wave activity, more similar to the EEG of relaxed wakefulness than the more synchronous NREM EEG.Periodic bursts of rapid eye movements (hence the name REM), variable autonomic activity, and atonia of skeletal muscles are other features of REM sleep."Deep" sleep (N3) is considered to be "restorative" in that it is associated with marked reductions in sympathetic activity resulting in decreased heart rate and blood pressure and stable breathing.Low amounts of N3 are associated with increased cardiovascular disease risk.8 The evolution Chronic sleep deficiency, defined as a state of inadequate or mistimed sleep, is a growing and underappreciated determinant of health status.Sleep deprivation contributes to a number of molecular, immune, and neural changes that play a role in disease development, independent of primary sleep disorders.These changes in biological processes in response to chronic sleep deficiency may serve as etiological factors for the development and exacerbation of cardiovascular and metabolic diseases and, ultimately, a shortened lifespan.Sleep deprivation also results in significant impairments in cognitive and motor performance which increase the risk of motor vehicle crashes and work-related injuries and fatal accidents.The American Academy of Sleep Medicine and the Sleep Research Society have developed this statement to communicate to national health stakeholders the current knowledge which ties sufficient sleep and circadian alignment in adults to health.