How much deep sleep do you need a night? It's probably less than you think

If you're asking yourself, 'how much deep sleep do I need?', you're likely to be pleasantly surprised by the answer

How much sleep do I need? Woman sleeping on mattress
(Image credit: Shutterstock)

How much deep sleep do you need? Getting enough sleep is fundamental to good health and wellbeing is by now something we're all familiar with. From increasingly sophisticated mattress designs, to pillow sprays and sleep tracking apps, there are countless sleeping aids out there that promise better, sounder sleep.

We also know that there are different sleep stages that we all go through during the night. Many of us have heard about REM (Rapid Eye Movement) sleep, which is the stage at which we're most likely to dream. But it's actually deep sleep that's the most important stage, responsible for tissue repair, memory consolidation, and immune system rebuilding.  

So, how much deep sleep do you need a night? The answer may surprise you: a healthy adult who gets the recommended seven to nine hours of sleep a night only needs about an hour to an hour and a half of deep sleep a night, or between 13 to 25 per cent. Yes, deep sleep is the rarest kind of sleep, but you don't need very much of it (although getting more deep sleep will definitely do no harm). 

A normal sleep cycle is about 90 minutes long and consists of a combination of REM, slightly different stages of light sleep (most of our sleeping is light sleep), and a bit of deep sleep. The problems begin when you don't get to the deep sleep stage at all, or not enough, which is what results in symptoms of sleep deprivation. 

How to make sure you get the recommended amount of deep sleep during the night? The most common reason for not being able to sleep deeply is stress, and for many people, removing the source of stress is what will give them better sleep. By all means take advantage of the sleep aids out there (a nice face mask and pillow spray have never hurt anyone), but if the reasons for your restless nights lie in your waking life, they're the ones you should try to prioritise resolving. 

Top tip: Sleep experts advise against lying in bed longer in hopes of getting more sleep. Too much sleep of bad quality has been linked to increased risks of depression and even heart problems.