How much sleep do you need?

how much sleep do you need

Sveti Williams, sleep coach and author, explains what sleep is, how it works and how much you really need. 

What is sleep?

Sleep is a highly complex and active process of dynamic restoration, rejuvenation, recuperation and reconsolidation, all of which are essential for health and wellbeing.  Sleep is a fundamental and highly complex biological phenomenon. Neurotransmitters in the brain control our sleeping patterns in interaction with neurons. Neurotransmitters such as serotonin and norepinephrine keep some parts of the brain active while we are awake. Other neurons at the base of the brain begin to signal when we fall asleep, ‘switching off’ the signals that keep us awake.  Chemicals are central to sleep, particularly adenosine, which is produced by our cells, accumulates in our blood and travels to the brain while we are awake and causes what we experience as sleepiness. This chemical gradually breaks down while we sleep and allows us to wake. Yes, sleep has a complex biology.

The stages of sleep

Sleep Cycle

Why we sleep

It is still not understood why humans and other animals evolved the need to sleep. What is clear is that sleep, like breathing oxygen, is a fundamental human requirement.  Studies into animals show that sleep is a prerequisite for survival. One study found that rats deprived of REM sleep survive only about 5 weeks on average, and rats deprived of all sleep stages live only 11–32 days. In comparison, a healthy rat will live for about 2-3 years.  The sleep-deprived rats developed a number of ailments, including abnormally low body temperature and sores on their tail and paws.  The sores that developed on the sleep-deprived rats seem to be evidence of an immune system imbalance caused by a lack of sleep.  Scientists believe that lack of sleep can have a similar detrimental effect on humans. Sustained sleep deprivation can lead to mental disturbance, anxiety, fatigue and even death. There are reports of cases where people have died after periods of no sleep at all.  In such cases, people experience symptoms such as hallucinations, weight loss and finally dementia before their death.  Sleep is so important to well-being that scientists argue that animals can survive for three times as long without food as without sleep.

How much sleep do you need?

It is widely accepted that people need approximately 8 hours of sleep every night, but this can vary from person to person. As each sleep cycle has a duration of about 90 minutes, and we need 5 such cycles, the total recommended sleep is 7.5 hours a night. Sleeping well depends not only on the number of hours, but on the quality and consistency of sleep.  A person can spend 10 hours in bed and still feel tired in the morning because they did not get enough deep sleep.

Sleep calculator

To calculate the sleep we require, and to know when we should be going to bed, we need to work backwards and define the time we need to wake up.  For example, if we need to rise at 7 am, we need to count back 7.5 hours, which brings us to 11.30 pm.  However, getting to sleep is a process.  Sleep onset latency is the period of time taken to fall asleep and should be about 10–20 minutes. Therefore, allowing for 20 minutes of sleep latency, 11.10 pm can be defined as the best bedtime to get the sleep you need, assuming a reasonable quality of sleep ensues. Interestingly, if you find yourself asleep as soon as you hit the pillow, this may be an indicator of sleep deprivation. If the onset of sleep takes longer than 20 minutes, this may be a symptom of insomnia.

Please note:  This article is not to be used as medical advice.  If you are considering a sleep treatment please consult your doctor or medical professional.  This post may contain affiliate links.

Author profile
Sveti Williams
Sveti Williams

Sveti is a Brisbane-based sleep coach and author of the book Fix My Sleep.  She bases her unique sleep-enhancing method on complimentary and holistic practices.  Click her to visit her website.

26 replies
  1. Caroline says:

    Very interesting post. I feel like the less sleep I get the more alert and less sluggish I am during the day but my biggest problem is getting to sleep and then waking during the night so I think I need to work on a wind down routine.

    • TheDeepSleepCo says:

      People need different amounts of sleep. Like Sveti said, it’s not really about how long you sleep for but the quality of sleep you get. Thanks so much for reading.

  2. Tatiane McGee says:

    Wow! This is super interesting! I didn’t know anything about the stages of sleep. It was great to understand how it works. Thanks for sharing

  3. Rawlings sunday says:

    Thanks for this facts on sleep you really enlightened me more.never knew that the consequences of not sleeping is that serious.

  4. Ruth says:

    Wow, this was a really interesting read! feel a little sorry for the rats though! It all makes sense and I definitely need to work on getting to bed that little bit earlier so that I have that period of time to wind down for sleep.

  5. Karlee says:

    I feel as long as I can wake up on my own without an alarm I am more refreshed than if I got the same amount of sleep and woke up to an alarm clock, I wonder if there is a science behind that. I didn’t know there was a time that you’re supposed to fall asleep in sometimes it takes maybe 20 minutes and other times it takes hours but is it still insomnia when that happens?

  6. Aimee says:

    I’m a 10+ hour a night kinda girl. Always have been. But sadly my wee 11mth old doesn’t subscribe to that notion. Living off lots of broken sleep and def falling asleep as soon as my head hits the pillow.

  7. Mica says:

    With two kids I know how tough sleep deprivation can be – those poor rats! It can be so hard to get the right amount of sleep when kids are little. My youngest was a fairly good sleeper until he was about 10 months old, then it got harder, haha! I’m used to running on less sleep now, but I do miss it!

  8. Julia Van Der Sluys says:

    Found this so interesting, especially the rat trials and how long they lasted! Just goes to show we need sleep. I struggle with sleep but slowly getting better!

  9. Marnie says:

    I found this so interesting – having had a baby who didn’t sleep well at all for over a year, I feel like I’m a little obsessed with learning about sleeping patterns! I think I need about 8.5h – 9h to wake up refreshed…tough requirement when you’re a parent!

    PS, poor rats!


Leave a Reply

Want to join the discussion?
Feel free to contribute!

Leave a Reply

Your email address will not be published. Required fields are marked *