Final answer:
The body repeats the sleep cycle of NREM and REM stages approximately 5 to 6 times in 8 hours of sleep, with each cycle lasting about 90 minutes.
Step-by-step explanation:
During a typical 8 hours of sleep, a person's body goes through several cycles of sleep stages, including NREM (Non-Rapid Eye Movement) and REM (Rapid Eye Movement) sleep. The average sleep cycle is about 90 minutes long, which means that in 8 hours of sleep, an individual would complete approximately 5 to 6 cycles. Each cycle includes stages 1, 2, 3, and finally REM sleep, which exhibit distinctive brainwave activity patterns as indicated in Figure 4.8. As the night progresses, the duration of REM sleep typically increases with each cycle. NREM sleep is characterized by slower brainwaves, while REM sleep showcases brainwaves similar to wakefulness, as shown in Figure 4.11.
A study noted that sleep needs vary by age, and that those over 65 average fewer than 7 hours per night. In addition, interventions like hypnotherapy or new medications can influence the amount of sleep one gets, as illustrated by various exercises and studies presented. Taken together, these processes and insights help us appreciate the complex nature of sleep and its essential role in health and wellbeing.