| Popis: |
Recent sleep research has attempted to understand the experience of effort, effort-related behaviors, and physiological indices of effort following sleep deprivation. How humans modulate their effort in response to internal resource limitations caused by sleep loss and the demands of environmental constraints is the focus of current research. Sleep loss affects the choices people make with or without their awareness. Subjective effort has been found to increase during the course of the sleep deprivation period as long as it is assessed during the sleep deprivation period and not following it. Subjective effort questions vary from laboratory to laboratory and require responses to queries about abstract concepts. Objective effort such as speed of response and work rates has been shown to decrease with sleep deprivation. More effective measures of effort involve offering performance choices. On these tasks, sleep-deprived participants reduce the task challenge and modulate the effort they apply. Motivationally rich environments including those with feedback or those which are personally stimulating can maintain performance at baseline levels for short periods. Assessment of physiologically-based compensatory responses, including glucose utilization and blood pressure, and recruitment of additional brain areas with a focus on the prefrontal cortex, the parietal lobes, and the nucleus accumbens, have been the focus of current sleep deprivation and effort research. Adenosine and dopamine have been implicated in effort reductions following sleep loss. The predominant theory used to explain changes in effort with sleep loss suggests that a loss of energy resources due to sleep deprivation is responsible for the cognitive and performance deficits observed. Following sleep, brain arousal and activation is facilitated through the use of stored energy resources. Under sleep-loss conditions, energy resources are either unavailable or too depleted to maintain normal performance. Brain structures monitor energy use, engage stored energy resources, and apply the needed effort to maintain performance if the task is motivationally engaging. However, the energy on which effort or compensatory activity depends is limited. The need for energy is system-wide, and only amounts that permit the sustainability of the organism will be expended. |
