How Does Sleep Work?

Have you ever wondered how exactly sleep works? It all revolves around a couple fascinating biological systems. These two systems in our bodies interact to influence when we sleep and when we are awake. One is sleep-wake homeostasis, and the other is circadian rhythm. Though these two systems work in a few similar ways, they each have specific functions to help you stay rested.

Sleep-Wake Homeostasis Chart

Sleep-Wake Homeostasis? What is that?

You may have already learned the term “homeostasis” in your biology class. Simply put, homeostasis is any system in your body that helps regulate important things like your blood sugar and temperature. Sleep-wake homeostasis acts as a sort of counter or timer within your body to help you sleep. It’s a simple balance when you consider it! If you’ve been awake for a long stretch of time, your urge to sleep will be stronger and you’re more likely to fall asleep. On the other hand, after you’ve slept for a while, the more likely you will be to wake up and stay awake.

How Circadian Rhythm Helps Us Sleep

The circadian rhythm, or day/night rhythm, is another key process in how sleep works. Circadian rhythms are 24-hour cycles that tell you whether you should be awake or asleep. It helps us stay awake during the day and allows our homeostatic sleep drive to push us into falling asleep and takes over to keep us asleep till morning comes. This balance is crucial to keeping you active during the day and getting the rest you need at night. Without it, your body and mind can be negatively affected.

Sleep-Wake, Circadian Drive Chart

How Does My Body Know When to Sleep?

A healthy balance between sleep-wake homeostasis and circadian rhythms allows you to sleep well. During your day at school, your homeostatic drive for sleep usually increases. This makes you more and more sleepy throughout the day. At the same time, your circadian rhythm shifts to the evening phase, where sleep-inducing melatonin is released into your body. Later in the evening, your brain begins to settle into sleep, with the rest of your body following shortly after. While you sleep, your circadian rhythm keeps the melatonin flowing, and your homeostatic drive for sleep fades away.

Once morning comes, the process is ready to repeat itself. When you wake up, your circadian rhythm stops the production of melatonin. This allows you to wake up and feel alert, in tune with the next phase of your day/night cycle.

Stages of Sleep

Sleep is about more than just dreaming! In fact, there’s a 3-stage process to how we all rest, divided between rapid eye movement (REM) and non-REM sleep:

  • Stages 1 & 2 – This is the “light sleep” phase, and it’s how your body transitions into a deeper sleep. In this phase, your muscles relax, your heart rate and breathing slow, and you’re more likely to wake up due to any outside disturbances.
  • Stages 3 – This is the “deep sleep” phase, and it helps your body repair itself overnight. During this phase, if you are a child or teen growth hormones are released. All ages experience increased blood flow to muscles and tissue growth while cells begin to repair themselves.
  • REM Sleep – This is the “vivid dream” phase that helps your mind stay sharp. At this stage, your brain activity runs high, your heart rate increases, your body experiences the inability to move, all while you experience a dream sequence before the process starts over from Stage 1 and cycles through again and again.

What Disrupts Sleep?

Getting good sleep is crucial to staying healthy and active, but there are some factors that can impact your ability to sleep, such as:

  • Light or Noise in your Room – Listening to loud music and keeping the lights on too late can fool your body into thinking it’s earlier than it is. Limit your exposure to both before bedtime.
  • Staying Up Late for School – Schoolwork is important, but not at the expense of your sleep schedule. Be sure to set a cutoff time so you can get ready to sleep.
  • Stress, Anxiety, or Depression – Falling asleep when you’re worried or concerned about something can be difficult. Try to find healthy ways to unwind before bed like yoga or writing in a journal.
  • Screentime Before Bed – Using your cell phone or laptop before bed can throw off your circadian rhythm and affect your quality of sleep. Try to save your social time for the next day.

So, now you can see how intricate the sleep process is and how much it helps you! Your body can’t restore itself without this crucial two-process model of sleep-wake homeostasis and circadian rhythm. By keeping these systems in balance and following healthy sleep habits, you can stay happy, healthy, and alert every day.