A good night’s sleep is essential for our health. But of course you have those days when the alarm goes off without you really feeling rested. The reason? Perhaps you were just in one of the wrong sleep phases when the alarm clock forced you out of sleep. How exactly do these sleep phases work?
Sleep contains structure
Every person spends an average of one third of their lives sleeping. And that is also necessary. Sleep restores our body and is essential for processing our daily information and experiences. To achieve this, a certain structure can be found in our sleep. Sleep is made up of so-called sleep cycles. The same sleep cycle is repeated four to five times a night, with each cycle lasting about 90 to 120 minutes.
How many sleep phases are there?
One sleep cycle, in turn, is made up of several sleep phases. On the one hand, scientists say that a sleep cycle consists of five phases, but according to others, you can distinguish four phases. We maintain five sleep phases. The first four phases fall under the first type of sleep: the Non-Rapid Eye Movement – no rapid eye movements – (NREM) sleep. The last phase, on the other hand, belongs to Rapid Eye Movement (REM) sleep. Time to take a closer look at all these phases.
Phase 1: sleep phase
The name already gives it away a bit. But this phase is between the state of being awake and the moment of falling asleep. The eyes close and the brain decides after a long day of work to get some rest: the brain activity decreases. The sleep phase only lasts a few minutes.
Phase 2: light sleep
You fell asleep. Annoying little noises won’t wake you up. If you do wake up during this phase, it will feel like you haven’t slept at all. You are in light sleep for just under an hour per sleep cycle.
Phase 3: transition phase to deep sleep
In this short, five-minute transition phase, your body prepares to fall into a deep sleep. We enter an ultimate state of relaxation. The body ensures that no muscle is tense, that breathing is at a regular pace and that the heart rate decreases.
Phase 4: deep sleep
As the name suggests, you are deep in your sleep. If you are abruptly awakened from this phase, for example by that annoying alarm clock, you feel confused. You need time to realize what kind of day it is and where you actually are. You are in deep sleep for just under 20 minutes. This phase is essential for the physical rest of our body.
Stage 5: REM sleep
During REM sleep, we are actively dreaming. That is why this sleep, in which we are constantly moving our eyes, is also called dream sleep. Our body relaxes the muscles, just like in deep sleep, but this time raises the blood pressure. It is during this phase that we can store information and certain experiences in our long-term memory. We experience dream sleep for about 20 minutes per cycle.
One sleep cycle is over. Will a new one start right away? Not equal. Sometimes we even wake up briefly, but often you don’t notice it. Our body will first check whether we feel pain, whether our bladder is perhaps too full and whether the environment is still safe. If we get the green light on these three points, a new cycle starts. And as said before, this is repeated four to five times a night.
What about your sleep phases?
Do you want to know about your sleep phases? Genetic factors play a role in various aspects of sleep. For example, you may be genetically a short or long sleeper, have an increased risk of insomnia, and your quality of sleep may be more or less compared to others. Get our Somnogenomics report now and find out your genetic traits when it comes to sleep!