Answer: The circadian and homeostatic processes in your brain work in tandem to maintain a 24-hour sleep/wake cycle.

Sleep and wakefulness is governed by the circadian process that runs on a 24-hour clock. These is controlled by an area of the brain called the hypothalamus, which sends signals through nerves to your pineal gland, which helps make melatonin. These chemical messages help keep your body tuned into its natural biological rhythm. In other words, it’s regulating all of these important processes for you! It tells you when to get up and go to bed every day… But this internal switchover from daytime alertness or high energy levels at alertness or arousal during daylight hours, to night time sleepiness or low energy levels during nighttime hours… is caused by your body’s circadian rhythm, also known as the sleep/wake cycle or pattern. Body temperature changes and wakefulness disorders can disrupt this pattern. For example, what time do you normally go to bed every night? An irregular schedule — one that varies considerably from day to day — can throw off your body’s internal clock and make it difficult for you to fall asleep. It’s important to go to bed at the same time every night — and wake up at the same time every morning — so that your sleep patterns return to a regular schedule.