“On average, REM sleep accounts for 20-25% of total sleep time in adults but it can vary widely anywhere between 5% and 50% depending on age, lifestyle and individual needs. Deep sleep, on the other hand, is the most restorative stage for the body, typically accounting for about 15-20% of total sleep.”

If you’re sleeping for eight hours, that means you should be looking to spend around an hour and 35 minutes in deep sleep and an hour and 45 minutes in REM sleep.

It’s important to note that getting too bogged down in the numbers isn’t a good idea and could make your sleep worse (there’s a term for insomnia triggered by an obsession with sleep tracking – orthosomnia). Not only is every sleep tracker different (which means data will vary depending on what device you use) but our sleep needs change depending on what we’re going through, so as long as you wake up feeling rested and ready to go, there’s normally nothing to worry about.

Instead, you can use these numbers to get a general idea of where your sleep is at and use lifestyle changes to achieve more of a balance. “It’s more helpful to look at your patterns over time,” Karsikas adds. “If your sleep regularly includes a healthy mix of both REM and deep sleep, your body and mind are likely getting the balance of recovery they need.”

What you can do about it

If you’re consistently getting a small amount of deep sleep – and you wake up feeling groggy and run down – then there are a few simple things you can do.

“If you have more REM sleep than deep sleep, it usually means your body is prioritising mental and emotional recovery,” Karsikas explains. “REM supports memory, learning and emotional regulation, so a higher share can reflect stress, irregular sleep or simply natural variation with age. It’s not harmful in itself but consistently low deep sleep may leave you feeling less physically restored.”

Because deep sleep is the point of the cycle where your body is most relaxed and your brain waves are the slowest, you need to create an environment and bedtime routine that is conducive to relaxation. Engaging in calming activities before bed, staying away from stimulants like coffee in the latter half of the day and making sure your bedroom is cool, dark and quiet can all help, as they allow your body to wind down. A consistent sleep schedule can also make a difference, as it helps to regulate your circadian rhythm and ensure your melatonin levels spike around bedtime to help you nod off into a deep slumber.

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