Monday ARTICLE #30: COGNITIVE EFFECTS- Sleep deprivation
Sleep is an everyday process that is essential for life and optimal health. It plays a critical role in brain function and systemic physiology, including metabolism, appetite regulation, and the functioning of immune, hormonal, and cardiovascular systems. The stages of sleep have commonly been divided into one stage of rapid eye movement (REM) sleep and four stages (Stages 1–4) of non-rapid eye movement (NREM) sleep. The deeper sleep stages (Stages 3 and 4) are collectively referred to as slow-wave sleep (SWS), which is believed to be the most restorative type of sleep and typically occurs during the first one-third of the night. In contrast, REM sleep increases as the night progresses and is longest in the last one-third of a sleep episode. REM and NREM sleep are characterized by numerous, yet different, physiologic changes, including brain activity, heart rate, blood pressure, sympathetic nervous system activity, muscle tone, blood flow to the brain, respiration, airway resistance, renal function, endocrine function, body temperature, and sexual arousal.(1)
Sleep deprivation occurs when you do not get the amount of sleep that is required by your body. It is an occurrence that affects people regardless of age, socioeconomic classes etc. A human’s cognitive functions are expected to be impaired following the severity of the lack of sleep, which produces impaired cognitive performance. For a deeper understanding, sleep deprivation specifically affects the psychomotor, cognitive speed,vigilant and executive attention, working memory, and higher cognitive abilities. To outline its statistics, sleep deprivation is prevalent in 20% of all adults, with the typical consequence of daytime sleepiness.
It poses risks to safe operation in all modes of transportation and to performance in other safety-sensitive activities. Improved understanding of the neural basis of such risks in operational environments has been achieved through the experimental study of how precisely sleep deprivation affects discrete cognitive abilities.
Through time, scientists have polished their understanding of the effects of sleep deprivation on human neurobehavioral functions after identifying the neural systems, which control the circadian and sleep homeostatic mechanisms. To dive deeper, it is well known to researchers that sleep-wake regulation is dependent on the neurobiology of hypothalamic mechanisms. However, less is known about how these systems interact and alter waking neurocognitive functions(2). Located in the suprachiasmatic nuclei(SCN) of the hypothalamus is the endogenous biological clock which modulates both wake-fulness and sleep, as well as waking behaviour.
Sleep deprivation impairs visual short-term memory and limits its capacity. A recent fMRI study(3) used parametrically manipulated perceptual or memory load in two visual tasks, and found that both tasks showed declines in behavioural performance and reductions in parietal and extrastriatal activation after sleep loss. Critically, sleep deprivation reduced the linear relationship between memory load and parietal activation at rested wakeful-ness. Attention lapses following sleep loss compared with those after normal sleep were associated with reduced activation in the visual sensory cortex and thalamus.
Symptoms of sleep deprivation
Mood and behavioural changes, including anxiety and depression
Short attention span, resulting in decreased reaction times
Problems with higher-level functions, such as planning, organization, and judgment
Psychiatric symptoms of sleep deprivation, such as disorientation, hallucinations, and paranoia
Physical effects (e.g gastrointestinal symptoms )
Van Dongen HPA, Dinges DF. Investigating the interaction between the homeostatic and circadian processes of sleep-wake regulation for the prediction of waking neuro-behavioural performance. J Sleep Res 2003;12(3):181–187
Chee MW, Chuah YM. Functional neuroimaging and behavioural correlates of capacity decline in visual short-term memory after sleep deprivation. Proc Natl Acad Sci U S A2007;104(22):9487–9492