What are the Stages of Sleep?

So, I’ve covered the essential question you need to ask yourself:  How much sleep do I need? And provided a sleep diary so you can determine how much sleep you are getting. Throughout the night the typical person will go through four stages of sleep, and cycles through these stages continuously.   In this post, I address the question: What ARE the stages of sleep?

REM vs. Non-REM Sleep

The first thing to understand is the difference between REM and non-REM sleep. REM simply stands for “rapid eye movement.”  During REM sleep, your eyes are closed, but they dart around in different directions; in non-REM, they don’t.

Non-REM Stages of Sleep

Stage 1 – Light sleep. You can easily wake up by noise or other disturbances. Your heart rate and breathing begin to slow, your eyes move slowly and your muscles relax.  

Stage 2 – Light sleep. In this stage, your brain waves slow down with occasional bursts of rapid waves. According to the National Institutes of Health, the typical person spends half of their night in this stage.  

Stage 3 – Very deep sleep. It is difficult to be awakened. At this point your brain produces extremely slow waves (Delta Waves) almost exclusively. This sleep is considered the restorative stage of sleep needed for you to feel well-rested and energetic the next day. If you are awakened in this stage, you will likely feel groggy and have a hard time engaging in a conversation.

REM Stages of Sleep

Stage 4 – Here is where it gets interesting. Stages 1 to 3 have been non-REM, sleep. Stage 4 is the first stage of REM sleep. In addition to rapid eye movement, your heart rate and blood pressure increase as your breathing becomes more rapid, shallow and irregular.

You’ve probably experienced a dream where you need to run or use your hands – but can’t. Interestingly, during REM, your arms and legs are temporarily paralyzed, so you can’t physically act out any dreams you are experiencing. This should be especially comforting for those who dream they are flying after falling from a tall building.

The Cycle Continues

Sleep during the night cycles continuously between the non-REM and REM stages. But how you get to REM sleep is not as easy as 1,2,3, so to speak.

The cycle is more complex. According to the Harvard Medical School*, you begin at Stage 1 and stay there 1 to 7 minutes.  Stage 2 lasts 10 to 25 minutes. Stage 3 lasts 20 to 40 minutes. From there you go back to stage 2 for 5 to 10 minutes. Then you enter Stage 4, which is REM sleep. This lasts about 10 minutes. This entire cycle will take from about 70 to 100 minutes. The cycle then begins anew, but subsequent cycles grow to between 90 and 120 minutes.

Age Matters

How much time you spend in each stage depends on your age. According to Web MD, infants spend 50% of their sleep time in REM sleep. Adults spend about half of their sleep time in Stage 2, about 20% in REM; the other 30% is divided between Stages 1 and 3. Here’s the really bad news, though: The older you are, the less time you’ll spend in REM sleep. But don’t give up hope. In subsequent posts, we’ll explore how to make the most of your sleep time.

Sources:
*Natural Patterns of Sleep: http://healthysleep.med.harvard.edu/healthy/science/what/sleep-patterns-rem-nremal Patterns of Sleep

This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.