How and why do we sleep, why do we dream?

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Sarah Messenger (0801595) SJPS5004

How and why do we sleep, why do we dream?

Considering the functions of sleep and dreams, it has been suggested that humans spend approximately one third of their lives asleep (cited in Goldsmith, 2005). However, there still remains no clear agreement on what the function of sleep is. This essay focuses on exploring how humans sleep, and possible explanations for why we sleep and why we dream.

It is believed that sleep follows a circadian rhythm, effecting sleep onset and stages (cited in Sanei & Chambers, 2007). The human biological circadian rhythm is roughly a 24 hour cycle, which is controlled by a circadian pacemaker. This "pacemaker" is the section of the brain known as the suprachiasmatic nucleus (SCN), which is situated in the hypothalamus (cited in Stickgold & Walker, 2009).

Signals produced by the SCN travel to different regions of the brain which controls the sleep-wake cycle within humans (cited in Kramer et al, 2001). The SCN regulates other functions associated with the sleep cycle such as body temperature, hormone secretion, urine production, and changes in blood pressure, which are all known to decrease during the sleep process. The SCN