Sleep is comprised of five stages and a continuous cycle of switching between these stages until the sleep is awakened. These stages are broken into two parts; the non-REM sleep stage that includes stage 1 to stage 4 and the REM sleep stage which is the final stage. This guide encompasses all important pieces of information regarding the 5 stages of sleep, sleep cycle and its stages, deep sleep, REM sleep, and changes that occur in sleep cycle with age. So without wasting any time, let’s start with;

The 5 Stages of Sleep:

Though there are typically 4 stages of sleep as the 4th stage was eliminated by the sleep profession in the US in 2008, and was merged in stage 3. But to give you a full picture, we will separately define stage 4 as well.

Stage 1:

Often referred to as light sleep, this stage is the first step towards sleep. This is where you drift into sleep and also out of it, meaning you are not fully asleep and can be awakened easily. Your eyes movement and muscle activity start to slow down, and this is where people sometimes experience the sensation of falling from a height and then contraction of the muscle.

Stage 2:

This is where the real transition to deep sleep starts. Your heart rate starts to slow down, and your body temperature also starts to drop. You enter in light sleep.

Stage 3:

This is where you dive into the deep sleep. Your brain waves become extremely slow and people in this experience sleepwalking, bedwetting, nightmares, and sleep talking.

Stage 4:

The subject will still be in a deep sleep in this stage. It is harder to rouse people, and if they are awakened, they will feel disoriented for a few minutes. This is the stage where your body starts to repair itself; your tissues start to regrow, bone and muscle building starts as well.

REM Sleep:

You may call it the fifth stage of sleep, but its scientific name is REM (Rapid Eye Movement) sleep. It is the final stage of sleep, and brain waves start to mimic the activities of waking state which means your eyes start to move rapidly from one side to another while staying closed.

What is Sleep Cycle?

Simply put, sleep cycle is the total period of time it takes for a person to move through all 5 stages of sleep mentioned above. One important thing to note here is that the order of these 5 stages of sleep is not straight. This means the sleeper does not go from non-REM (stage 1 to 4) to REM sleep. The sleeper goes from light sleep to deep sleep and then reverts back to light sleep and then moves to the REM sleep. To eliminate any confusion, please refer to the example below:

The sleeper first moves from stage one to stage 2 (both are light sleep stages) then from stage 2 to stage 3/4 (these are deep sleep stages) then from these stages of deep sleep to the stage 2 and then stage 1 of light sleep and then finally to REM sleep.

Note: After the REM sleep stage, the sleeper returns to stage 1 (light sleep), and the cycle starts again.

Stages of Sleep Cycle:

  • Waking Stage: This is where the person is in full consciousness and can answer intelligently. You can also call it Stage 0.
  • Light Sleep: This is where stage 1 and stage 2 of sleep lie. The person transitions between waking and sleeping in the first stage and then drifts to light sleep which is stage 2.
  • Deep Sleep: The deep sleep stage encompasses stage 3 and stage 4 of sleep. The brain waves become extremely slow especially in stage 4 which are recorded with electroencephalogram (EEG), a device to evaluate the electrical activity of the brain.
  • REM Sleep: It can also be called Stage R. Brainwaves start to pick up the pace and eventually become similar to the waves when the person is awake. The sleeper witnesses most vivid dreams in Stage R.

What is Deep Sleep?

It is comprised of stage 3 and stage 4 of the sleep cycle. It is also called as delta sleep or slow wave sleep. During this stage, the person is so deep in sleep that it is a bit difficult to wake him up. This is where bedwetting, night terror, sleepwalking, sleep talking or vivid dreaming starts. This is the sleep where our growth hormone is released, and our body starts to recover. If you experience a tiring day, and you are able to get a deep sleep, upon waking up, you will feel fresh and active.

When Does REM sleep Occur?

The slow wave sleep which encompasses light and deep sleep occurs in the first half of the night and then comes the REM sleep in the second half of the night. The average time it takes for an individual to enter into REM sleep is 90 minutes after he falls asleep. As we talked above that the cycle from light sleep to REM sleep continues until you wake up, the first cycle that ends at REM sleep will last for about 10 minutes. And each successive REM cycle will last longer than its preceding REM cycle.

Changes in Sleep Cycle with Age:

There is a change in sleep cycles with the change in age. Less age means more REM sleep, and with the increase in age, timing of REM sleep decreases. For instance, infants typically spend about 50 percent of their sleep time in REM sleep while the adults spend about 20 percent in REM, 50 percent in stage 2 (light sleep) and the rest 30 percent in other three stages. And as the adults get older, their REM sleep timing will start to decrease.

  • Firmness Level

    The Nectar uses good quality memory foam on top which provides good pressure relief but also uses one of the best foam cores we have reviewed.  Under the top layer it has very firm support under the comfort layers so your back stays in good alignment.

  • Memory Foam / Price

    The memory foam layers on top ensure you have very good pressure relief.  The gel infused top quilt layer ensures the mattress doesn’t get as hot as regular memory foam.  It cradles your lumbar and supports the lower back like a high end mattress but the price is very competitive.

  • Firmness Level

    The Layla firmness is optimal for combo sleepers but also has a firmer side so you will most likely find the firmness that works best for you.

  • Copper Infused Memory Foam

    Copper infused foams have been known to help with the bodies ability to heal.  The foam Layla uses is also top notch for pressure relief.

Brentwood Home Oceano

  • Firmness Level

    The Oceano firmness is optimal for combo sleepers but has a good firmness level that will provide good support for back pain.

  • Coil on Coil

    The Oceano removes one layer of foam and has a 2nd coil unit on top of the support base coil unit.  In my opinion this design offers premium support where it’s needed most and also good breathability paired with motion isolation.

  • Firmness Level & Latex Support

    The Avocado uses latex foam.  This can be a great choice for those seeking firmer support with added bounce and those who do not want the “stuck” feeling of memory foam.

  • Latex + Coils

    The Avocado pairs latex with hybrid coils.  This combination will provide excellent bounce, and more of a sleeping on the mattress vs in the mattress.  The latex is very durable and will provide firmer support for those seeking less sinkage and better support for low back pain.

Optimal Mattress Firmness for Back Pain

When selecting a mattress for chronic back pain, it’s important that you also consider firmness. While research is limited in this area, one study evaluated over 300 people with lower back pain and found that approximately 82% of individuals that used medium-firm mattresses reported decreased pain, compared to 68% sleeping on firm mattresses. Another study supported this research and found that medium-firm mattresses reduced back pain by approximately 48%, and improved sleep quality by 55%.


Patients who used medium firm mattresses were more likely to have improvements in pain related disability than were patients who used firm mattresses (table). The groups did not differ for improvement in pain while lying in bed or improvement in pain on rising