symptoms similar to:
Attention-deficit hyperactivity disorder (ADHD)
Psychosis
TL;DR post about mental effects below
Sleep deprivation can adversely affect the brain and cognitive function.[19] A 2000 study, by the UCSD School of Medicine and the Veterans Affairs Healthcare System in San Diego, used functional magnetic resonance imaging technology to monitor activity in the brains of sleep-deprived subjects performing simple verbal learning tasks.[20] The study showed that regions of the brain's prefrontal cortex displayed more activity in sleepier subjects. Depending on the task at hand, the brain would sometimes attempt to compensate for the adverse effects caused by lack of sleep.
The temporal lobe, which is a brain region involved in language processing, was activated during verbal learning in rested subjects but not in sleep deprived subjects. The parietal lobe, not activated in rested subjects during the verbal exercise, was more active when the subjects were deprived of sleep. Although memory performance was less efficient with sleep deprivation, greater activity in the parietal region was associated with better memory.
A 2001 study at Chicago Medical Institute suggested that sleep deprivation may be linked to more serious diseases, such as heart disease and mental illnesses including psychosis and bipolar disorder.[21] The link between sleep deprivation and psychosis (psychiatric disorders) was further documented in 2007 through a study at Harvard Medical School and the University of California at Berkeley. The study revealed, using MRI scans, that lack of sleep causes the brain to become incapable of putting an emotional event into the proper perspective and incapable of making a controlled, suitable response to the event.
A noted 2002 University of California animal study indicated that non-rapid eye movement sleep is necessary for turning off neurotransmitters and allowing their receptors to "rest" and regain sensitivity which allows monoamines (norepinephrine, serotonin and histamine) to be effective at naturally produced levels. This leads to improved regulation of mood and increased learning ability. The study also found that REM sleep deprivation may alleviate clinical depression because it mimics selective serotonin reuptake inhibitors (SSRIs).
This is because the natural decrease in monoamines during REM is not allowed to occur, which causes the concentration of neurotransmitters in the brain, that are depleted in clinically depressed persons, to increase. Sleep outside of the REM phase may allow enzymes to repair brain cell damage caused by free radicals. High metabolic activity while awake damages the enzymes themselves preventing efficient repair. This study observed the first evidence of brain damage in rats as a direct result of sleep deprivation.[22]
Animal studies suggest that sleep deprivation increases stress hormones, which may reduce new cell production in adult brains.[23]
Among the numerous physical consequences of sleep deprivation, attention deficits are perhaps the most important; attentional lapses in mundane routines can lead to unfortunate results, from forgetting ingredients while cooking to missing a sentence while taking notes. The attentional lapses also extend into more critical domains in which the consequences can be literally life-or-death; traffic accidents and industrial disasters can result from inattentiveness attributable to sleep deprivation.
To empirically measure the magnitude of these attention deficits, researchers typically employ the psychomotor vigilance task (PVT) which requires the subject to press a button in response to a light at pseudo-random intervals. Failure to press the button in response to the stimulus (light) is recorded as an error, attributable to the microsleeps that occur as a product of sleep deprivation.
Crucially, individuals' subjective evaluations of their fatigue often do not predict actual performance on the PVT. While totally sleep-deprived individuals are usually aware of the degree of their impairment, lapses from chronic (lesser) sleep deprivation can build up over time so that they are equal in number and severity to the lapses occurring from total (acute) sleep deprivation. Chronically sleep-deprived people, however, continue to rate themselves considerably less impaired than totally sleep-deprived participants.[27] Since people usually evaluate their capability on tasks like driving subjectively, their evaluations may lead them to the false conclusion that they are able to perform tasks that require constant attention when their abilities are in fact impaired.
