Sleep deprivation is a common phenomenon. Social scientists lament it as a problem in modern times, but it is difficult to be certain whether sleep deprivation is truly a new issue. Certainly there are individuals and groups who consider the ability to function with little sleep to be an indicator of robust physical health or even a symbol of superior personal willpower.
Individual and societal attitudes about sleep may vary, but scientific investigations into the body’s response to sleep deprivation consistently points to overall negative physiologic effects.
Sleep Deprivation and the Body
Evidence shows that sleep deprivation has an adverse impact on alertness, decision-making, reaction time and high-level cognitive function. Chronic sleep deprivation impairs a number of facets of physical wellness, such as exercise recovery, hypersensitivity to pain, and the risk of cardiovascular disease. The biological basis of such effects is not fully understood, but research is beginning to reveal some of the cellular processes that occur as the result of sleep deprivation.
Cerebral Alterations Resulting from Sleep Deprivation
Studies that evaluate the pathophysiologic changes that occur during sleep reveal some interesting findings, particularly in terms of cerebral changes. A number of studies confirm the effects of sleep deprivation on long-term memory, and it is believed that this effect may be partially related to impaired synaptic plasticity, which can alter the number and function of cerebral neurons involved in memory.1
Sleep deprivation has an established effect on the synaptic consolidation that is required for the hippocampus to adequately function in storing and retrieving memories.2 Currently, the mechanism by which impairment of synaptic consolidation occurs has not been well established or understood. Recent studies have revealed that sleep deprivation specifically impairs hippocampal cAMP and mTOR signaling, and causes spine loss in CA1 neurons.
A recent study designed to characterize the effect of short-term total sleep deprivation on plasma amyloid-β (Aβ) concentrations corroborated the impact of sleep deprivation on neuronal changes that can result in memory loss, although through a somewhat different mechanism.3 In 20 healthy adult volunteers, total sleep deprivation increased morning plasma Aβ40 levels by 32.6% and decreased the Aβ42/Aβ40 ratio by 19.3%. Furthermore, a positive relationship was found between the duration of total sleep deprivation and plasma Aβ40 level and Aβ40/Aβ42 ratio. Volunteers also had significantly lower plasma concentrations of LDL receptor-related protein after sleep deprivation. Impaired peripheral Aβ clearance is postulated among the possible causes for these findings. And interestingly, increased oxidative stress is another possible cause of the study findings. Increased oxidative stress is often considered to be the basis of a number of different disease processes.
Consequences of Sleep Deprivation
The consequences of sleep deprivation are diverse, and they affect almost every organ system in the body. The exact cause of the negative effects induced by sleep deprivation is not quite clear, and even the negative effects in the brain may be produced by various biochemical mechanisms.
1. Havekes R, Vecsey CG, Abel T. The impact of sleep deprivation on neuronal and glial signaling pathways important for memory and synaptic plasticity. Cell Signal. 2012;24:1251-1260.
2. Havekes R, Abel T. The tired hippocampus: the molecular impact of sleep deprivation on hippocampal function. Curr Opin Neurobiol. 2017;44:13-19.
3. Wei M, Zhao B, Huo K, et al. Sleep deprivation induced plasma amyloid-β transport disturbance in healthy young adults. J Alzheimers Dis. 2017;57:899-906.