REM, Light & Deep: How Much Sleep Should I Get a Night?

Quality sleep is an essential pillar of health and wellbeing. Whilst it is possible for someone to survive on very small amounts of sleep, your body and mind need a certain amount of good quality sleep to function properly. This is not just related to being tired and grouchy throughout the day — poor sleep hygiene can have negative effects on many areas of your health.

With ever-busier work and social lives, it can be hard to feel like you have the time to get enough sleep. However, sleep debt — that is the cumulative effect of not getting enough sleep every night — will soon have a noticeable effect on your overall health and wellbeing. Here, we look at the different types of sleep, and how much you need to get in order to reap the benefits.

How much sleep do I need?

Generally speaking, sleep experts recommend that most healthy adults need seven to nine hours of sleep every night. That being said, achieving restful sleep does not necessarily depend on how many hours of sleep a person gets — the quality and type of sleep you get are equally important in reaching optimal sleep hygiene. To determine your individual sleep requirements, consider Dr Rangan Chatterjee’s ‘RATE’ chart below.ⁱ

How do you RATE your sleep?

Key

0 – Never or rarely  1 – Occasionally  2 – Almost always

A score of 0 illustrates poor sleep quality, while a score of 6 is brilliant. Anything under 6, however, indicates you could benefit from improving your sleep hygiene. Discover ways to improve your sleep quality and wake up energised here.

Can you oversleep?

In short: yes.

If you constantly feel tired, or sluggish, then your automatic response may be to sleep more. However, it’s possible that you are oversleeping. If you are consistently resting for upwards of nine hours and still feeling lethargic or excessively fatigued, it could be that you are sleeping too much. Just like under-sleeping, oversleeping can also disrupt your circadian rhythm and make you feel drained of energy throughout the day.

You may need to reset your body clock, to re-align yourself with your circadian rhythm. Everyone needs different amounts of sleep to function, but as a starting point, try limiting your sleep to seven to nine hours per night.

Oversleeping can also sometimes be a symptom of an underlying health condition; learn more about the causes of oversleeping here.

What are the different stages of sleep?

As we sleep, the body enters a state of rest and repair. Many processes happen during this time. You should aim to go through five or six full sleep cycles per night, in order to feel well-rested and allow your body to benefit from the restorative processes.

Each sleep cycle typically lasts 90 minutes and moves through the four stages of sleep. The first three stages comprise of non-rapid eye movement (NREM) sleep, and the fourth is when rapid eye movement (REM) sleep happens. Each phase has unique characterisations where different aspects of our physiology are affected, including eye movements, brain wave patterns, and muscle tone.

Stage 1  of NREM sleep

This is the lightest stage of NREM sleep. Typified by slow eye movements, this lethargic stage of sleep can be easily broken by arousals or awakenings. Your muscle tone relaxes and brain wave activity begins to slow down from wakefulness. Sometimes, you can experience hypnic jerks — a sudden jerk of your entire body — or the sensation of falling as you drift off.  Overall, you spend a very short amount of time in Stage 1. 

Stage 2 of NREM sleep

This is the first stage of defined NREM sleep. Arousals and awakenings don’t happen as much as in Stage 1. Your slow eye movements stop, while your brain waves continue to wind down, with only short bursts of activity. Your heart rate and body temperature begin to decrease, too. Stage 2 comprises of roughly 40-60% of your total sleep time.ⁱⁱ

Stage 3 of NREM sleep

This is the deep stage of NREM sleep. As a more nourishing and restorative stage of slumber, arousals and awakenings are rare. Often, it’s very difficult to rouse someone in stage 3 sleep. Sleepwalking and night terrors can occur in this deepest stage of sleep, too. Stage 3 doesn’t last as long as Stage 2, only making up 5-15% of total sleep time in adults.ⁱⁱⁱ

REM sleep

At this final stage, you have transitioned into a deep, restorative sleep, which involves vivid dreams and heightened brain activity. Your body becomes temporarily paralysed during REM sleep to prevent you from acting out your dreams. Awakenings and arousals can also happen more easily in this stage, too. If you’re woken during REM, you’ll feel groggy, overly sleepy, and disorientated.

As the name would suggest, this fourth sleep phase is defined by periods of rapid eye movements. The reason for such movements is largely still a mystery, however, it’s believed they’re related to the visual images of dreams. Longer periods of REM sleep occur during the final hours of sleep (generally in the early morning), meaning those who do not spend a full 7-9 hours in bed are usually deprived of the rejuvenating benefits. For most adults, REM sleep makes up about 20-25% of sleep.^iv

Why is REM sleep so important?

Usually, if you can remember your dreams when you wake up, this means you are getting good quality REM sleep. Scientists are still unsure why REM sleep is so beneficial for our brains and bodies.

One theory is that a chemical associated with stress, norepinephrine, isn’t secreted during REM sleep. The ‘REM calibration hypothesis’ suggests REM sleep can actually reset the levels of norepinephrine^v. When this happens, your brain is less sensitive to stimuli. A study published in the Journal of Neuroscience found that participants who spent more time in REM sleep had significantly lower fear-related brain activity when they were given mild electric shocks the following day^vi. In many ways, then, the deep sleep stage can help to regulate the chemicals secreted by our brains, affecting how we react to different situations throughout the next day.

Sleep is one of the most important aspects of overall health, and poor sleep hygiene can have many negative knock-on effects on your physical and mental wellbeing. To find more information on common sleep disorders, as well as how you can improve your sleep hygiene, feel free to visit our sleep health hub.
 

References:

1. Chatterjee. R. (2017). The 4 Pillar Plan: How to Relax, Eat, Move and Sleep Your Way to a Longer, Healthier Life. Penguin Life. 210.

2. Institute of Medicine (US) Committee on Sleep Medicine and Research. Colten. H.R. & Altevogt. B.M., editors. Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem. Washington (DC): National Academies Press (US), 2, Sleep Physiology. (2006). Available online: https://www.ncbi.nlm.nih.gov/books/NBK19956

3. Institute of Medicine (US) Committee on Sleep Medicine and Research.

4. Institute of Medicine (US) Committee on Sleep Medicine and Research.

5. Gujar. N., McDonald. S.A., Nishida. M. & Walker. M.P. (2011). A role for REM sleep in recalibrating the sensitivity of the human brain to specific emotions. Cerebral cortex. (New York, N.Y. : 1991), 21(1), 115–123.

6. Lerner. I., Lupkin. S., Sinha. N., Tsai. A. & Gluck. M.(2017). Baseline Levels of Rapid Eye Movement Sleep May Protect Against Excessive Activity in Fear-Related Neural Circuitry. The Journal of Neuroscience. 37(46), 11233-11244.

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Olivia

Olivia Salter has always been an avid health nut. After graduating from the University of Bristol, she began working for a nutritional consultancy where she discovered her passion for all things wellness-related. There, she executed much of the company’s content marketing strategy and found her niche in health writing, publishing articles in Women’s Health, Mind Body Green, Thrive and Psychologies.

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