How Much Deep Sleep Do You Need?

Deep sleep, also known as slow-wave sleep, is the most restorative stage of your sleep cycle. It’s when your body repairs tissues, strengthens the immune system and relaxes the muscles. But how much deep sleep do you actually need?

Experts suggest that deep sleep should account for about 20 to 25% of total sleep. Since the recommended amount of sleep for adults is at least 7 to 8 hours per night, this equates to roughly 1.4 to 2 hours of deep sleep.

Your sleep is divided into non-REM (75%) and REM (25%) stages, with deep sleep forming part of the non-REM portion. However, the amount of deep sleep you get naturally changes with age. Babies, children, and teenagers typically need more deep sleep, as it’s important for growth and development. Older adults and pensioners tend to experience much less deep sleep, as overall sleep duration decreases with age.

Lifestyle factors also play a role. Stress, caffeine intake, and inconsistent sleep schedules can all disrupt deep sleep, making it harder to get the restorative rest your body needs. So, prioritising good sleep habits can help maximise your deep sleep and keep you feeling refreshed and energised.

So, now that you know how much deep sleep you should be getting, the real question is, are you actually getting enough? And if not, what can you do about it? Let’s dive deeper (pun intended) into what deep sleep really is and why it matters.

Deep sleep is a stage of NREM (non-rapid eye movement) sleep, which usually occurs during the third stage of your sleep cycle. During this stage, your body is at its most relaxed and won’t wake easily, even from loud noises. You may feel groggy or tired if you wake up during deep sleep.

During deep sleep, you experience specific physiological changes, including:

• A slower heart rate and breathing
• Relaxed muscles
• Brain waves at their slowest during your entire sleep cycle

Deep sleep occurs for more extended periods during the first half of your sleep, with the longest stretch happening soon after you fall asleep. This stage can last between 45 and 90 minutes but gradually shortens with each sleep cycle until it eventually stops.

This stage of sleep is the most restorative. During deep sleep, our bodies work to repair and grow, which is essential for recovery. It is also when energy is restored, so if you wake up still feeling tired in the morning, it’s likely you haven’t had enough deep sleep.

‘Deep sleep is also when the pituitary gland secretes important hormones, like human growth hormone, leading to growth and development of the body.’

Healthline

Deep sleep is when most energy restoration, cell regeneration, and tissue repair occur. Blood that is not being used by the resting brain is redirected to your muscles, helping to heal not only muscular issues but also immune and nervous system problems.

In addition to its physiological benefits, deep sleep is also the stage in your sleep cycle where you process information. A lack of it means your brain can’t effectively convert the information you’ve absorbed throughout the day into memory. That’s why cramming for an exam the night before rarely works, especially without a good night’s rest.

Deep sleep is, therefore, extremely important for physical and mental health, and not getting enough of it has been linked to health problems later in life. A recent study by the Washington University School of Medicine found that adults who do not get enough deep sleep have higher levels of a brain protein called tau, which is associated with Alzheimer’s disease.

The best and easiest way to accurately track how much deep sleep you get is by using a sleep tracker on a smartwatch or fitness device. These devices monitor your heart rate and movements to estimate the time spent in each sleep stage. They can also compare your data to the average for people of your age and gender. Another way to assess whether you lack deep sleep is by how tired you feel the next day. If you’re more tired than usual or consistently fatigued, chances are you’re not getting enough.

Not sure where to start? Try our Sleep Cycle Calculator to plan your perfect bedtime and wake-up schedule, optimising your sleep cycles for better rest and more deep sleep.

There’s no single way to increase the amount of deep sleep you get. However, improving your overall sleep quality and duration can help. Here are some tips to enhance your sleep:

• Stick to a consistent sleep schedule – Going to bed and waking up at the same time every day helps regulate your body clock.
• Create a bedtime routine – Take a warm bath, read a book, or drink calming herbal tea. Avoid heavy meals and caffeine close to bedtime, as they can disrupt your sleep.
• Limit screen time before bed – Blue light from phones, TVs, and laptops suppresses melatonin (the sleep hormone) and tricks your body into thinking it’s daytime.
• Exercise regularly – Aim for 20–30 minutes of movement daily. It doesn’t have to be intense—even a walk helps! Just avoid working out too close to bedtime, as it can be stimulating.
• If you can’t sleep, don’t force it – Instead of tossing and turning, get up and do something relaxing like gentle yoga or reading.

The short answer is no—deep sleep doesn’t cause nightmares. However, it has been linked to sleepwalking, night terrors, bedwetting, and even sleep-eating. These issues aren’t caused by deep sleep itself; they just tend to happen during this stage.

Most of these problems stem from stress and anxiety experienced while awake. If sleep troubles keep you up at night, don’t hesitate to check in with your GP; they can help you find the best way to rest easily.

Read our article for more ways to calm feelings of anxiety for better sleep.