Sleep is needed in order for the human body to be able to function normally, with humans spending on average one-third of their life sleeping (Murali, Svatikova & Somers, 2004). The sleep-wake cycle is a circadian rhythm, meaning that the human sleep-wake cycle roughly corresponds to periods of daylight and night time, therefore repeating itself every twenty four hours. Within the sleep/wake cycle there are 5 stages, the 5th stage is known as rapid eye movement (REM) sleep, this is the stage in which people dream.
Dreams are able to be categorised by their perceptual features, with the features being consistent across a range of studies. These studies show and demonstrate how visual events are present in almost all dreams, with; auditory information
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PET scans have also shown that global brain metabolism is comparable between wakefulness and REM, with cognitive and neural organisation in dreaming and waking being consistent (Yuval & Tononi, 2010).
During REM sleep there has also been found to be a reduction in the activity in the prefrontal cortex; the area of the brain associated with self-awareness. This evidence has then been used to argue that this could be in order to prevent people from realising their dreams aren’t real and why dreams then appear to be real, as well as possibly explaining time distortions that occurs when dreaming (Maquet et al, 1996).
Animal studies have also been used in order to help explain what occurs within the brain when a person is dreaming. For example, during REM sleep muscular atonia is normally induced through the inhibition of spinal motor neurons by the ponto-bulbar reticular formation. Research using cats found, that when the reticular formation has lesions, the cat was unable to suppress the normal muscular paralysis that occurs during REM sleep, therefore showing various motor behaviours (Lai & Siegel, 1999). This evidence implies there is regionally-specific brain activity during REM sleep, with the regionally-specific brain activity including motor