Final answer:
One's sleep cycle changes across the lifespan, with different sleep patterns observed at different ages. Sleep is influenced by biological rhythms, external factors, and individual differences in circadian patterns. There are several stages of sleep characterized by specific brain wave patterns.
Step-by-step explanation:
One's sleep cycle changes across the lifespan. When we are very young, we spend up to 16 hours a day sleeping. As we grow older, we sleep less. By the time we are 65 years old, we average fewer than 7 hours of sleep per day. This change in sleep patterns is influenced by biological rhythms and external factors such as light. Individual differences in circadian patterns, known as a person's chronotype, also affect sleep-wake cycles.
During sleep, there are several different stages characterized by specific patterns of brain wave activity. These stages include NREM sleep and REM sleep. NREM sleep is divided into three stages, with brain waves transitioning from alpha waves to theta waves to delta waves. REM sleep is characterized by rapid eye movements and brain waves similar to wakefulness.