Human Sleep-Wake Cycle - Essay Example

In the decrement of circadian processes, sleep homeostasis takes charge, allowing for sleep opportunities to dominate (Martinez-Rodriguez & Santamaria, 2005). As part of biological rhythm, patterns in sleep-wake cycle may vary, depending on developmental age, but some of its mechanisms remain the same. Anatomical Description Neurological in origin, sleep-wake cycle is governed by brain structures, which in turn regulates neurochemical mechanisms. On structural construct, hypothalamus in midbrain is home to suprachiasmatic nucleus, which primarily controls circadian patterns of being awake and asleep (Conn, 2006).

Progressively, arousal states in consciously-aware individuals are governed by several neurological parts: “brainstem.thalamus, and basal forebrain.” These anatomic landmarks are sources for several neurotransmitters, which chemically influence the sleep-wake cycle--promoting active or passive stimulation. Specifically, wakefulness is generated by chemical reactions with “hyprocretin and locus coeruleus in hypothalamus and dopamine in thalamus,” while sleepiness is induced by “serotonin in brainstem and prostaglandin in forebrain” (Stiller, & Postolache, 2005, p. 2008). Each is either inhibited or exploited in order to maintain balance between wakefulness and sleepiness.

If a part malfunctions, other neurochemicals compensate, before disruptions in sleep-wake cycle manifest. . In stage 1, there is initial drowsiness and progression towards light sleep. On the next stage, light sleep deepens into true sleep--consistently repeated at midnight. In the last two stages, 3 and 4, biologic functions are slower, and slow-wave category of sleep takes place. This frequently occurs early in sleeping episodes and account for less than a quarter of overall sleeping time. As NREM has been through, more active brain activity signals entry into REM.

Brain stimulation is intensive compared to previous levels in NREM, with distinctive “rapid eye movement.muscle paralysis, and dreaming” (Davis & Parker, 2004). As NREM occupies earlier periods of sleeping time, REM is exhibited during early mornings. In cyclical manner, sleep levels must pass from phases in NREM to REM, and constantly repeated as the chain is through--to achieve restful sleep. Sleep-wake Changes in Age Development Between the lengths of staying awake and falling asleep, there is a supposed difference in this aspect for young and older groups.

Length of continuous sleep is shortest in newborns, with less than 4 hours, and increases by 2 hours as they get older--totaling to 14-16 hours per day. In adolescence stage, 10 to 12 hours of sleep is common (Davis & Parker, 2004). Nonetheless, shortened sleep in young children lengthens with age augmentation, and declines as old age approaches. Significantly, circadian wake indicator is an hour or two earlier in older ones; hence, the range between staying awake and falling asleep is no longer proportional to that of younger samples (Billiard & Kent, 2003).

The source for such alteration is traced back to circadian rhythm, where diminished natural processes change the older generations’ ability to stay asleep. As circadian