The Psychology of Sleep Cycles and Disorders

There are five stages of sleep that cycle throughout the sleep process (Gerrig and Zimbardo pp.162-165) stage one, stage two, stage three, stage four, and non-REM sleep. Occasionally a sixth step is identified as waking. (The Sleep Channel, sleepdisorderchannel.com/stages.) The waking stage begins the sleep cycle. It is often referred to as relaxed wakefulness and is the period where the body prepares to sleep. As the body relaxes from the tense awake state, muscles relax, a feeling of sleepiness overtakes the person, and eye movement slows. At this relaxed state, stage one sleep begins. (The Sleep Channel.)

During stage one, sleep brain waves are emitted at 3 to 7 cps. (Gerrig and Zimbardo pp.162-165) There is a 50% reduction in body and brain activity seen in wakefulness and stage one of the sleep cycle. Eyes are also closed during this phase of sleep but if a person is awoken during this phase they will not feel as if they have slept. (The Sleep Channel.)

Sleep spindles, mild bursts of electrical activity or 12 to 16 cps, characterize stage two sleep. (Gerrig and Zimbardo pp.162-165). Stage two is also characterized with light sleep where stillness of the body is disrupted by periodic muscle twitches. Physical symptoms during this stage include slowed heart rate, and body temperature drop. This is a transitory period from light sleep to deep sleep. (The Sleeping Channel.)