On average, adults get about seven hours of sleep per day. Sleep is an important aspect in everyone's lives and plays a role in our performance, function, and overall health.
When we think of sleep, a lot of times people look at the quantity of how many hours they may get rather than the quality of hours. For instance, have you ever felt groggy after waking up, even though you slept for a sufficient number of hours? It might come down to not getting through the cycles of sleep efficiently. There are many things that go into how we feel after sleeping. Let's dive a bit deeper to uncover the stages of sleep and what each of them mean.
The initial stage of sleep is known as the dosing off stage and really only lasts 1-10 minutes. During this stage, the body is preparing for sleep and transitioning into the next sleep stage. As an easy reminder, this period is where we see the bobbing of the head, continually waking ourselves up and falling back into sleep.
Stage two of the sleep cycle is called the relaxation phase. Again, this second stage is further preparing the body for even deeper sleep. We can still be woken up in this stage fairly easily. Our body temperature and blood pressure are lowering, and there is an alternation between muscle tone and muscle relaxation.
Once we are past the initial two stages, we then move into deep sleep. It's during this stage that if we get woken up and interrupted from completing the full deep sleep phase, we may feel groggy. The body's muscles are the most relaxed in this stage, and brain waves, blood pressure, and body temperature are at their lowest. We spend anywhere from 0-35% of our total sleep in this stage, with most of that percentage being accumulated in the front half of sleep for the night. The significance of racking up enough deep sleep is that growth hormone is increased during this phase, which contributes to the body's restoration and repair of tissues. If you're looking to make physical body adaptations, then this is a phase you won't want to sleep on! (Pun fully intended.)
The fourth and final stage of sleep is classified by rapid eye movement – that's to say that the first three stages of sleep involve non-rapid eye movement, or NREM, making this fourth stages stand out as REM sleep. This is when we dream! The brain's activity increases from deep sleep and we enter into creative thinking, hence where we start to dream, sometimes vividly. On top of that, our memories from the day go from short-term to long-term storage during this phase of a sleep cycle. REM sleep will start dominating in the latter half of the night and makes up about 5-50% of our total sleep.
So, what does all this information mean to you? By understanding the sleep cycles better, you may be able to see where you struggle and why you may feel groggy or physically tired some days compared to others. On average, it is best to aim anywhere from 7-10 hours of sleep, allowing for about 4-6 cycles of sleep to get through all the stages sufficiently. You can then craft for yourself your exact needs, as each human has an individualized requirement. All stages of sleep are important, so by giving focus to not only quantity of sleep but also quality, you can tackle all angles of health during your most restful part of the day!