Sleep. It’s something our bodies require, but how much do you actually know about it? I remember briefly learning about the sleep cycles in college and that it intrigued me, but that’s all I remembered. So here is what I’ve been learning.
Let’s jump straight to the interesting part. We have a sleep cycle that is four stages, and healthy individuals cycle through about 5 to 7 times per night. Sleep experts say that the average cycle length is about 90 to 120 minutes.
Here’s what happens in each stage of the sleep cycle.
This is when you’re just drifting off. Your body is starting to relax and you’re able to be woken up easily during this stage.
Fun fact: If you typically hit your snooze button in the morning, your body is stuck in this stage between those intervals. That’s why you never really feel more rested.
This stage is called non-REM (non-rapid-eye-movement). Your muscles begin to relax even more and your heart rate begins to slow down. Dr Harris says, “This is the first true stage of sleep.”
Fun fact: Your body temperature lowers during this stage. This is referred to as thermoregulation. This allows homeotherm mammals (humans, dogs, tigers, etc) to save energy in non-REM sleep without the brain getting so cold that it is unresponsive to threat.
This is the restoration stage. Your body repairs itself during this phase. Growth hormone is released to relieve your body from the stresses of the day. Now that your muscles are relaxed and breathing has slowed the immune system performs the necessary tasks.
Fun Fact: It is hard to wake up from this stage of sleep.
This is when we enter deep sleep, this stage is called REM (rapid eye movement). This is where we dream and our imaginations run wild (you can dream in the other stages too, but it happens the most here). Your brain also processes information during this stage. This is important for learning and memory.
Fun Fact: All of our voluntary muscles besides our eye muscles act as though they’re paralyzed. This is also the phase where you can experience disorders like sleep paralysis, night terrors, etc.
Ultimately sleep affects almost every tissue in our body and not getting the proper amount of sleep can really impact our health.