Effects of sleep deprivation on cognitive performance

It has been estimated that over 20% of adults suffer from some form of sleep deprivation. Insomnia and sleep deprivation are common symptoms of depression and can be an indication of other mental disorders. The consequences of not getting enough sleep could have dire results; not only to the health of the individual, but those around them as sleep deprivation increases the risk of human-error related accidents, especially with vigilance-based tasks involving technology. It has been estimated that over 20% of adults suffer from some form of sleep deprivation. Insomnia and sleep deprivation are common symptoms of depression and can be an indication of other mental disorders. The consequences of not getting enough sleep could have dire results; not only to the health of the individual, but those around them as sleep deprivation increases the risk of human-error related accidents, especially with vigilance-based tasks involving technology. The parietal lobes of the brain are largely involved in attention. Lesions to this region of the brain in humans result in difficulty or inability to attend to events that are contralateral to the lesioned hemisphere. Those with lesions to the posterior parietal lobe have little to no difficulty shifting attention to and from stimuli appearing in the space ipsilateral to the lesioned hemisphere. However, they do display a slowed response in shifting their focus of current attention to events and stimuli appearing contralateral to the lesioned hemisphere. Studies involving single-unit recordings from the parietal lobes of monkeys have indicated that there are neurons solely involved in integrating visual spatial information with postural information. Without this apparent combining of spatial information, it would be difficult or impossible to locate objects in external space, as information provided solely by the retina is insufficient. The position of the eyes, head and body must also be taken into consideration. In addition, studies involving transcranial magnetic stimulation application over the parietal lobes as well as positron emission tomography (PET) analysis of the parietal lobes suggest that this region is involved in conjunction searches, but not in single-feature searches. (See Visual search for supplementary information.) Auditory attention has been examined following sleep deprivation. Researchers examined the auditory attention of twelve non-sleep-deprived subjects and twelve sleep-deprived subjects at various time intervals. Subjects were involved in an auditory attention task, which required the reproduction of the spatial relationships between four letters, using a graph composed of six squares, immediately following the presentation of an item from a tape recorder. It was found that auditory attention of sleep-deprived individuals is affected as the total amount of sleep-deprivation increases, possibly due to lowered perceptual vigilance. Functional magnetic resonance imaging (fMRI) scans of the brains of subjects exposed to thirty-five hours of sleep deprivation indicate that sleep deprivation is related to increases in prefrontal cortex and parietal lobe activation during tasks that combine verbal learning and arithmetic. This is particularly apparent in the right hemisphere. In non sleep-deprived individuals involved in verbal learning and arithmetic tasks the anterior cingulate cortex and the right prefrontal cortex are active. Following sleep deprivation there is increased activation of the left inferior frontal gyrus and the bilateral parietal lobes. This information suggests that divided attention tasks require more attentional resources than normally required by a non sleep-deprived individual. Studies using event-related potential (ERP) recordings have found that twenty-four hours of sleep deprivation decreases ERP response to signal inputs from endogenous, but not exogenous, sources. Therefore, it is suggested that sleep deprivation affects endogenously driven selective attention to a greater extent than exogenously driven selected attention. Twenty-four hours of sleep deprivation has been found to affect the functional connectivity between the inferior frontal parietal region (IPS) and the parahippocampal place area (PPA). However, sleep deprivation does not affect the attention modulation index of the PPA. With this information, researchers have concluded that the psychophysiological interaction (PPI) is more involved in selective attention than the IPS and PPA. Research has found that together, attention and sleep deprivation modulate the parahippocampal place area (PPA) activation and scene processing. Specifically, sleep deprivation was related to significant decreases in PPA activation while attending to scenes and when ignoring scenes. This is explained by the absence of change in the Attention Modulation Index (AMI). Face recognition is not affected by sleep deprivation.