Why Do We Need 8 Hours of Sleep A Night? Let's Take A Look

Not everyone gets enough hours of sleep a night. I believe it’s time to re-focus on the importance of getting enough good quality sleep.

Over 30 years of sleep research has produced a huge amount of data around what happens when we do and don’t get enough sleep, and what ‘enough’ sleep means. The introduction of functional MRI scanning opened up a whole new area of sleep research as scientists could start to see what was going on in the brain both during sleep and during waking hours as a result of varying amounts of sleep. For more on the benefits of sleep take a look at this article. 

The consensus is that we need 8 hours of sleep a night.

Let’s look at that in more detail.

Most people know that we have different phases of sleep:

  • Light sleep
  • Deep sleep
  • R.E.M. or Rapid Eye Movement sleep

But what is less well known is that we have sleep cycles throughout the night.

Each sleep cycle lasts approximately 90 minutes (and hour and a half) and the ideal number per night is 5.

5 x 1.5 hours = 7.5hours

plus 20-30 minutes to drop off gives us 8 hours (approximately).

However, not all sleep cycles are equal, and we need to go through each one in turn to ensure we get the most benefit from our sleep and stay healthy. As you can see from this diagram each sleep cycle has varying amounts of the different types of sleep.

*Note: NREM is non-REM sleep. REM is marked in purple.

8 hours of sleep a night

What Happens During The Different Stages Of Sleep?

During Non-REM sleep the body is healing, repairing  regenerating, and growing.

During REM sleep the emotional and psychological stuff of life is processed and memories are stored. This is when our brains bring together memories from past and current dilemmas and help us with problem solving and strategies. When we say we need to ‘sleep on it’ about a particular situation, what we need is the REM type of sleep. 

In the early part of the night, particularly during the first 3 sleep cycles, we have proportionately more Non-REM sleep than in the later part.

So the danger is that, if we cut our sleep short by getting up early, we miss out on a huge chunk of the extremely useful REM sleep.

There are many effects both physiological and psychological, of short sleep such as:

  • reduced immunity
  • reduced emotional intelligence
  • slower response times
  • less rational and more reactive to situations during the day
  • lack of focus and concentration
  • we can appear older and more stressed
  • we can find it harder to maintain a healthy weight

So, if you are looking to get up earlier in the mornings, make sure you work backwards 8 hours and calculate what time you need to be getting your head down to ensure you still get your 8 hours of sleep a night.

And if you find yourself waking in the night, that’s fine. Take a look at the chart above again and you’ll see that at the end of the 2nd and 4th sleep cycles, our brainwaves pop up a little into wakefulness. This is when, if your bladder is anywhere near full, it will encourage you to take a trip to the bathroom. You’re probably not waking (in most cases) because you need to pee. More than likely you’re nearly awake anyway so your body decides to notice it needs it.

The trick to going back to sleep and into your next sleep cycle is to stay in a nice super-relaxed state, so here are some tips: Don’t…

  • put a light on
  • speak
  • pick up your phone
  • do anything that spikes your brainwaves and gets you thinking


  • Move slowly (if you do need to take that trip to the bathroom)
  • Just tell yourself you’re at the end of a sleep cycle (this works amazingly well)
  • Focus on your breathing or do another simple meditation technique to keep your brainwaves sleepy

Do you have trouble getting to sleep? Take a look at my Deep Sleep Meditation

top tips for a better nights sleep

Drift Off To Sleep Naturally With

My 'Deep Sleep' Meditation

A 30 minute long  ‘Deep Sleep’ meditation.

Unlike my other meditations, this one has no 'call-back' at the end to return you to wakefulness. This means you can drift off to sleep while listening to it.

Just make sure it's not added to a playlist or set up so that the next track to play jolts you nastily out of your comfortable sleepy bliss.


Ideally, it is designed to be listened to last thing at night, or should you wake and be unable to get back to sleep. (Preferably cosy and warm snuggled up in your bed).

Price: £7.99

Use the coupon code HLBSMED to receive a 25% discount. 


Helen Leathers

Transformational Women's Coach, Trainer, Speaker & Author

Combining a spiritual outlook, a pragmatic approach, and a sense of humour I want to help you remember who YOU are and reveal YOUR path so you can step on to it empowered, energised, inspired and guided.

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