How Much Deep Sleep You Need?

How much deep sleep do you need

Given you are getting your recommended 8 hours, you as a human will spend around 33% of your life asleep. That's a pretty big chunk of time. But if you think spending 1/3 of your life drifted away in slumber is time wasted, you are far from the truth.  

The answer to "How much deep sleep do you need" differs from person to person. Sleep is when your body can rebuild, recuperate and re-energise for the following day and most of this happens during what is known as deep sleep, 1 of the 5 stages of sleep. Stage 1 and 2 are stages of light sleep, 3 and 4 stages of deep sleep, and 5 is referred to as REM sleep. REM meaning rapid eye movement.  

In a complete sleep or "good sleep" you will go through all 5 stages of sleep.

What is Light Sleep?  

Stage 1 is the time spent drifting in and out of sleep. This is the stage when first going to sleep. Stage 1 is usually brief and quick to transition into stage 2. This first stage can be experienced in the familiar scenario of falling partially asleep during a film but waking up every few seconds.  

Stage 2 is also light sleep, but you start to experience complete relaxation, the slowing down of your heart rate, a drop in body temperature and less conscious thoughts. Your transition into a steadier stage of sleep.  

What is Deep Sleep?  

Stage 3 is the start of deep sleep. Your breathing slows down along with your heart rate and body temperature to their lowest levels. This is when sleep becomes a more established state and you may be difficult to wake up.  

Stage 4, now fully set in deep sleep the body can work at its peak to repair damaged tissue, balance blood sugar and regulate your metabolism and immune system. Emotional recovery also takes place where the chemical balance in the brain is restored through a process of detoxification.  

What Percentage of Sleep should be Deep?  

It is advised that between 15% and 25% of sleep should be in stages 3 and 4 of deep sleep. Achieving ample amounts of deep sleep is essential to feeling well-rested and recovered. Those who do not manage to enter the deep sleep stage for this duration may begin to feel the effects of sleep deprivation, which can lead to many adverse effects:  

What is deep sleep

  • Memory issues: During deep sleep, your brain forms memory connections that help you remember and process things that you have seen and leaned. Without enough deep sleep, these connections won't be made.  
  • Trouble with concentration: Not getting enough deep sleep can lead to a lack of concentration and trouble thinking clearly. Your ability to solve problems efficiently is impaired.  
  • Mood swings: Ever referred to someone as "not a morning person"? This is probably because they are having troubles with getting enough deep sleep. Sleep deprivation can lead to lowered mood, quick temper spells, and increased anxiety.  
  • Weakened immune system: To little time spent in the deep sleep stage compromises your body's ability to properly restore your immune system. This leaves you more vulnerable to viruses and illness when coming into contact with harmful germs.  
  • Low sex drive: Studies show that those who are regularly sleep-deprived find that they have significantly lower libido, this is especially common in men. If not enough deep sleep is achieved the body can not regulate hormones properly, so there is the potential for testosterone imbalances leading to low sex drive. 


How Long Does the Deep Sleep Stage Last?

How long should a deep sleep cycle last is dependent on many factors, including age, health status, and stress levels? It is recommended that babies get on average 16 hours of sleep per day, which would mean 2-4 hours of that sleep should be in the deep stage. Adults, on the other hand, are recommended to have around 8 hours, which would work out to 1-2 hours. As you get older, your deep sleep duration decreases.  

If you are injured or sick you may find that your body needs more deep sleep, regardless of age. The same goes for a stressed mind which may cause strain across the entire body. This, in turn, would result in the need for more deep sleep as a means to repair and regulate both the mind and body.  

Is Too Much Deep Sleep Harmful?  

How much deep sleep is healthy depends entirely on your individual body's needs. There is no such this as having too much deep sleep, and there is certainly nothing to suggest that too much of it can harm you. There are however studies to suggest that getting too much sleep (in any stage) can leave you feeling as fatigued as getting too little. This puts forward a theory that any significant alteration sleeping routine can have a negative effect on fatigue levels.  

Is REM Sleep Deep Sleep?  

Too much deep sleep

REM sleep, or rapid eye movement sleep is an occurrence that happens throughout the night. REM sleep is a spike in brain activity that happens around every 90 minutes. Your blood pressure, breathing and heart rate raises to nearly awake levels, and your eyes quickly move around whilst still closed in a somewhat twitching motion. REM sleep is the stage when you are most likely to experience vivid dreaming and sleep talking.

Although activity levels in the brain are at their highest, REM sleep is the deepest of all the sleep stages. When in the REM stage, sleepers can fall into a temporary state of paralysis to stop involuntary movements caused by dreaming. Sleepwalking and talking only occurs during the REM stage also.  

Stages of REM sleep are essential for restoring the mind. It is when the brain can best perform tasks, such as processing information and emotions, produce memory connections and balance its own chemical makeup.  


How much deep sleep you need is entirely dependent on the circumstance that can change daily. What is most important is focusing on getting enough quality uninterrupted sleep, and your body will do the rest.  

Establish a comfortable environment in which to rest, destress yourself and give your body time to unwind. Limiting your screen time closer to the day's end will help to relax your mind, mindfulness techniques such as meditation and yoga can also aid in a good nights rest, essential for achieving enough deep sleep time.