Good sleep isn’t just about the number of hours you get each night. Some studies suggest the quality of your sleep might be more important for your wellbeing. But what exactly is good quality sleep? And how can you get more of it?
It turns out your sleep cycles are key. A sleep cycle is made up of 4 different stages of sleep. You need to pass through 4 to 6 of these cycles in the night to get the quality of sleep that restores and repairs your body and mind.
In each sleep cycle, you go into deeper levels of sleep and then rise up at the other side, before going into your next cycle. When you come closer to the surface between each one, you may or may not wake up briefly. The first 3 cycles are non-REM (rapid eye movement) sleep, which scientists usually call NREM sleep. The stages get deeper until the final stage, REM sleep.
Why sleep stages matter
Different things happen in the different sleep stages so disruption to any of them can affect your wellbeing. Scientists think missing out on deep and REM sleep is most damaging to your health, as these stages are when your body and brain are repaired. Research suggests the problems with thinking, emotions and physical health linked with poor sleep are mainly to do with lack of deep and REM sleep.
Experts sometimes talk about ‘sleep architecture’, which means the overall structure of your sleep. When you have healthy sleep architecture, you go through the right number of cycles and spend enough time in each of the different stages. Get it nailed and you’re likely to feel more refreshed and energised during the day.
The stages of sleep uncovered
Most sleep science says there are 4 stages of sleep. But some experts include the stage when you’re awake and moving towards sleep as another stage, making 5 altogether - so we’ve added it in here too.
Stage 0: Feeling drowsy
In this phase, you’re just beginning to move towards sleep. The alpha brainwaves linked to restfulness start to take over.
Sleep stage 1: Dozing off (N1 sleep)
This is the light sleep you have when you first fall asleep. You also go back to it briefly in each sleep cycle through the night. You can be woken up very easily in N1 sleep.
- what are the benefits? Your body and brain activity start to slow to prepare you for the next stage
- how long does it last? Just a few minutes in each cycle. It makes up around 5% of total sleep
Sleep stage 2: Relaxing (N2 sleep)
In the second NREM phase, your muscles relax, breathing and heart rate slow and your temperature drops.
- what are the benefits? This sleep stage helps you learn and lay down memories, and lets your brain block out things that might keep you awake. A key sign of N2 sleep is bursts of brain activity (scientists call them sleep spindles) – and a type of brainwave pattern called K complexes
- how long does it last? About 10 to 25 minutes in your first sleep cycle but it tends to be longer through the rest of the night. We spend about half our time asleep in N2 sleep
Sleep stage 3: Deep sleep (N3 sleep)
This is when your body’s at its most relaxed. You won’t wake up very easily from deep sleep. Even loud noises, like thunder, might not wake you. If you do wake up from N3 sleep, you’re likely to feel disorientated. Studies show you might feel groggy for 30 minutes to 1 hour if you wake up from this deep sleep phase.
- what are the benefits? Sleep researchers think this stage is important for creativity, memory and insight. It’s also needed for repair work - regrowth of tissue, building bone and muscle and strengthening your immune system. Your brain activity slows into a pattern known as delta waves so this stage is sometimes called delta sleep or slow-wave sleep
- how long does it last? Around 20 to 40 minutes in the early sleep cycles but for less time as the night goes on
Stage 4: REM sleep
REM sleep is named after the very fast eye movement that goes on behind closed lids in this phase. You go into it when you’ve been asleep for about 90 minutes. When scientists look at brain activity in REM sleep, it looks similar to what’s seen when you’re awake. This phase is when you have the most vivid dreams. But your muscles are paralysed – apart from the ones involved in breathing and eye movement. That’s so you don’t move around and hurt yourself while you’re dreaming. Your breathing becomes irregular.
- what are the benefits? REM sleep is thought to be essential for memory and learning
- how long does it last? In the earlier sleep cycles, REM sleep can last just a few minutes – but you’re in it for around an hour in later sleep cycles. REM sleep makes up about 25% of sleep in the average adult, but babies and very young children spend about half their sleep in the REM stage
Improving your sleep cycle
Start with basic sleep hygiene – creating the right conditions can help regulate your sleep architecture and give you the best chance for quality sleep. It’s hard to overstate the importance of getting into a routine, going to bed and waking up at roughly the same time. Read our article on science-backed tips for more ideas that may help.
Sleep cycle problems - and how to solve them
There are several things that can affect your sleep cycle and how long you spend in the important later sleep stages. So tackling some of these key issues can help you get better quality sleep:
- avoid alcohol, especially in the 2 to 3 hours before bed. It cuts the amount of REM sleep you get early in the night but gives you longer REM stages later on. This means it can affect your sleep quality, leaving you tired the next day.
- tackle your wake-up triggers. Focus on sorting out anything that makes you wake up a lot in the night. That could be sleep apnoea, restless leg syndrome or an unhelpful sleeping environment (with lots of background noise or an uncomfortable bed, for example). If you wake up lots, you’re likely to spend more time in the lighter sleep stages and not enough in the later ones.
- consider your sleeping pills. Some can reduce the time you spend in deep and REM sleep, including the types of antihistamines that make you drowsy. Read more about medicines for sleep - and always talk to your doctor before changing the way you take any prescription.
- make routine a top priority. Getting poor or irregular sleep for a few days can disrupt your sleep cycles. To shift back to a healthy sleeping pattern, making sure you go to bed and get up at the same time each day can really help.
- manage sleep disorders. Narcolepsy affects your brain’s ability to control the sleep-wake cycle and means you go into REM sleep very quickly. In sleep paralysis, your brain and body are out of sync as you move in or out of REM sleep – you’re conscious and wakeful but your muscles are still paralysed, so you’re temporarily unable to move.
When to see a doctor
If you’re always tired during the day, see your doctor – even if you think you’re sleeping for a full 8 hours, it may be that you’re not getting into the later sleep stages that restore you, whether that’s because of an underlying condition or something else. Your doctor can help you work it out.
Your health questions answered
Can you hack your sleep cycles?
‘If your morning alarm goes off when you’re in the middle of a sleep cycle, you’re likely to feel groggy and keep hitting the snooze button. So some people have tried to find ways to make sure they only wake up after a full cycle. One way is a DIY sleep cycle hack - you count back 90 minutes (the length of a typical cycle) from when you need to wake up and set your alarm to go off at that time, then set a second alarm for the time you really need to get up. The theory is that setting the first alarm lets you go back to sleep for a full cycle before the ‘real’ alarm goes off, so you wake feeling refreshed. You can also get trackers that give you information on your sleep, based on how much you’re moving around, so you can programme them to wake you when you seem to be in a light sleep phase. But there’s no research behind DIY sleep cycle hacking and trackers aren’t accurate enough to pinpoint different sleep stages, though may show you some general patterns that give you information about your sleep and what might be affecting it. The best ways to hack your sleep cycles are the tried and tested ones - make sure you’ve got your sleep hygiene sorted and have a regular sleeping and waking routine. If you’re concerned about sleep problems, you should always talk to your doctor.’
Want more tips on how to sleep like a baby? Try out our 28-day in-app sleep better plan for all the latest hacks on how to drift off more quickly and have better quality slumber. Currently available on iOS only.
