FAQ: What Are Sleep Stages?

What Are the Sleep StagesWhen your head hits the pillow and you head into dreamland each night, you actually experience four sleep stages while you rest. It can feel as though you’re just shutting off for several hours. However, there’s actually a lot going on while you snooze.

Throughout your rest, you’ll go through a number of cycles. Every one of those cycles is made up of four different sleep stages. They all have different properties, purposes, benefits and activities.

Focusing on progressing through all four phases in a healthy way is important to your overall wellness. Sleep interruptions can cause health problems. They could even be the reason you aren’t seeing weight loss results. Consider the following sleep stages and how they affect your body, mind and rest.

Sleep Stages 1 – NREM

NREM occurs once your eyes are closed, and you start to “drift off.” While that drifting phase occurs, you’re sleeping only very lightly. Of the sleep stages, this is quite a short one. It usually lasts for somewhere between one and ten minutes. During this phase, you can head to the next stage or you could easily return to being awake once again.

Here are some interesting facts about the first of the sleep stages:

• Even though you’re technically sleeping, if you wake up from the first of the sleep stages, it can feel as though you didn’t fall asleep at all.
• Your breathing will slow down from your waking rate, and you will maintain a steady heartbeat.
• Both your blood pressure and the temperature of your brain will fall.
• During NREM, your muscles will not yet be inhibited – that happens in later sleep stages. That said, your eyes may move around, and your eyelids may open slightly.
• If you have ever felt the sensation that you suddenly tipped over or fell, it happened during this phase. That sudden sharp movement that forces us awake, sometimes with a racing heart, is known as the hypnic jerk and occurs in the first of the sleep stages. Some believe this is a vestigial reflex. If that is the case, it may have been developed back when our ancient ancestors slept in trees. Those that would suddenly wake to stop themselves from falling out of a tree were most likely to survive. Hypnic jerks occur more frequently among people with irregular sleeping habits.

If you ever experience nights in which you feel as though you didn’t sleep but you don’t entirely remember being awake the whole time, either, you likely spent quite a bit of it in NREM, possibly not progressing further.

Sleep Stages 2 – NREM Stage 2

Once NREM Stage 2 kicks in, you’ll start to move into a deeper level of sleep. This is not the ultra-light level from the first of the sleep stages. It is at this point that people will typically feel that they have actually fallen asleep if they awaken.

Here are some interesting facts about the second of the sleep stages:

• The NREM Stage 2 lasts for approximately 20 minutes.
• Once the second of the sleep stages begins, the heart rate slows more than it had during the first phase. The body temperature also falls.
• Your brain waves start to become larger than they were in NREM.
• The body decreases its overall activity in many of its functions to prepare itself to move into a deeper level of sleep. For example, blood pressure levels start to fall, and your metabolism and its related functions will slow down.
• It is more difficult to wake you in NREM Stage 2 than it would have been in the first phase.

Combined, the NREM and NREM Stage 2 sleep stages are known as “light sleep.” Despite the fact that the second phase is deeper than the first one, deep sleep is not yet achieved at this point.

That said, this phase makes up a considerable amount of the total time among the sleep stages. NREM Stage 2 on its own makes up about 45 percent of the total length of time you’re asleep in an average night.

Sleep Stages 3: NREM Stage 3

For many years, the third was the last phase. However, more recent developments in sleep medicine have discovered that the final phase was actually made up of two sleep stages, which are now the third and fourth.

Here are some interesting facts about the third of the sleep stages:

• NREM Stage 3 usually begins 35 to 45 minutes after you first drift off.
• Brain scans using electroencephalograms reveal that when you’re in this phase, your brain waves are larger and slower. This is the phase often known as “Delta” sleep or the “slow wave” sleep.
• During this part of your rest, you are often able to sleep through many types of possible disturbances that might have woken you during the first two sleep stages. You’re more likely to remain asleep through certain noises and movements, particularly familiar ones, without disruption or reaction.

This is a much deeper form of sleep than the first and second sleep stages. As a result, if you are woken while you’re in NREM Stage 3, you will typically feel groggy and disoriented. This sensation typically takes a few minutes to wear off.

Sleep Stages 4 – REM

REM is the last of the sleep stages. The letters stand for Rapid Eye Movement. It usually begins once you’ve already been asleep for around an hour and a half.

Here are some interesting facts about the fourth of the sleep stages:

• The REM phase will typically last for about ten minutes. That said, throughout the night as you progress from one cycle to the next, REM can become longer. The final REM stage of the night can be an hour long.
• During REM, your eyes move quickly in all directions. This helps to explain how the phase got its name.
• This is the phase in which you get the deepest sleep.
• The heart rate and respiration rates will – unlike the previous three phases – increase. Their rhythms may become less regular as well.
• The most powerful dreams will usually occur during the ten-minute spans in which you remain in this part of the cycle.
• People who sleepwalk or wet the bed are most likely to do so while they are in the REM phase of sleeping.

Another name sometimes used to describe REM is “paradoxical sleep.” The reason for that alternative name is because of the brain waves that occur while it is happening. They can often appear quite similar to the brain waves the same person would have while completely awake. Moreover, the brain waves can show heightened activity during this phase.

This makes it important that REM is among the phases in which your muscles are typically paralyzed. Otherwise, you would be prone to movements in response to some of the thoughts or dreams you are having.

With a better understanding of the complexity of your sleep, it’s easier to understand why naps are meant to be short – typically around 20 minutes long – and why your snooze button isn’t necessarily your best friend. When it comes to the snooze button, you may already have moved into he second stage of sleep by the time it goes off, leaving you feeling groggy. Moreover, if you nap for longer than about 20 minutes, you risk moving into the third stage, from which you will wake feeling disoriented and foggy instead of alert and rested.

The more you work with your natural sleeping cycles, and the more regular you keep them, the better rested you may become over time.

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