Department of Mathematics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH, UK.
Department of Mathematics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH, UK.
Sleep Med Rev. 2016 Aug;28:96-107. doi: 10.1016/j.smrv.2015.05.011. Epub 2015 Jun 30.
Sleep changes across the lifespan, with a delay in sleep timing and a reduction in slow wave sleep seen in adolescence, followed by further reductions in slow wave sleep but a gradual drift to earlier timing during healthy ageing. The mechanisms underlying changes in sleep timing are unclear: are they primarily related to changes in circadian processes, or to a reduction in the neural activity dependent build up of homeostatic sleep pressure during wake, or both? We review existing studies of age-related changes to sleep and explore how mathematical models can explain observed changes. Model simulations show that typical changes in sleep timing and duration, from adolesence to old age, can be understood in two ways: either as a consequence of a simultaneous reduction in the amplitude of the circadian wake-propensity rhythm and the neural activity dependent build-up of homeostatic sleep pressure during wake; or as a consequence of reduced homeostatic sleep pressure alone. A reduction in the homeostatic pressure also explains greater vulnerability of sleep to disruption and reduced daytime sleep-propensity in healthy ageing. This review highlights the important role of sleep homeostasis in sleep timing. It shows that the same phenotypic response may have multiple underlying causes, and identifies aspects of sleep to target to correct delayed sleep in adolescents and advanced sleep in later life.
睡眠会随着生命周期而变化，青少年时期会出现睡眠时机延迟和慢波睡眠减少的现象，随后慢波睡眠进一步减少，但在健康衰老过程中逐渐提前。睡眠时机变化的机制尚不清楚：它们主要与昼夜节律过程的变化有关，还是与清醒时依赖于神经活动的稳态睡眠压力积累减少有关，或者两者都有关？我们回顾了与年龄相关的睡眠变化的现有研究，并探讨了数学模型如何解释观察到的变化。模型模拟表明，从青少年到老年，典型的睡眠时机和持续时间的变化可以通过两种方式来理解：要么是由于昼夜节律觉醒倾向节律的振幅和清醒时依赖于神经活动的稳态睡眠压力积累同时减少所致；要么是由于稳态睡眠压力单独减少所致。稳态压力的减少也解释了健康衰老中睡眠更容易受到干扰和白天睡眠倾向降低的原因。这篇综述强调了睡眠稳态在睡眠时机中的重要作用。它表明，相同的表型反应可能有多种潜在原因，并确定了睡眠的各个方面作为目标，以纠正青少年的睡眠延迟和晚年的睡眠提前。
