Light sleep, deep sleep and REM all form part of a normal night. Understanding the stages and rhythms of sleep can help you make sense of your nights and build habits that support better rest.
🕒 7 min read
What are the stages of sleep?
Sleep has four stages: three stages of non-rapid eye movement sleep, called N1, N2 and N3, followed by rapid eye movement, or REM, sleep. N3 is deep sleep; REM is the stage most associated with vivid dreaming. You move through these stages in repeated cycles rather than spending the whole night in one state.1, 2
It's not just that we feel grumpy and out of sorts after a run of late nights. Sleep affects how we feel and function during the day. While most of us try to catch up when we can, it helps to understand the patterns that make up a normal night.
| Stage | What happens | Where it fits |
|---|---|---|
| N1: light sleep | The transition from wakefulness into sleep. Breathing and heart rate begin to slow. | A short settling-in stage from which you can be woken easily. |
| N2: light sleep | You are asleep, your muscles relax further and body temperature falls. | Repeated throughout the night, making up a substantial part of total sleep. |
| N3: deep sleep | Slow-wave sleep, with slower brain activity and greater difficulty waking. | Usually more prominent in the first part of the night. |
| REM sleep | The brain becomes more active, eyes move rapidly and most muscles are temporarily very relaxed. | Vivid dreams are common, with longer REM periods later in the night. |
Both non-REM and REM sleep matter. It is more useful to allow enough time for a full night's sleep than to focus on maximising a single stage.1, 2
How long is a sleep cycle?
A cycle commonly takes around 80–100 minutes, although its length and the time spent in each stage vary. Most nights contain several cycles, and brief awakenings can happen between them. Deep sleep tends to occur earlier, while REM periods become longer as the night progresses.1
This means sleep is not a series of identical 90-minute blocks. You do not need to calculate bedtime around an exact number of cycles. Most healthy adults need around seven to nine hours, with individual needs varying.3
Natural rhythms: your body clock and sleep pressure
Your sleep-wake rhythm is influenced by your internal body clock and the sleep pressure that builds while you are awake. Light helps signal when it is time to be alert, while darkness supports the normal evening rise in melatonin. These signals work together with your daily routine.4
Going to bed and getting up at roughly the same time daily can help establish your personal sleep-wake routine. As we get older, our sleep patterns can change, including the amount of deep sleep. That is different from assuming everyone needs the same stage percentages.
A clean sleep: habits that support a restful night
Experts often call this 'sleep hygiene' – basically focusing on changing habits to encourage good sleep. Start with a few manageable adjustments rather than trying to perfect every part of your evening.3, 5
- Keep a regular routine. Try to get up at a similar time each day and go to bed when you feel sleepy.
- Make your bedroom restful. Keep it dark, quiet and a comfortable temperature. Reserve the bed for sleep or sex where possible.
- Give yourself a wind-down period. Reading, gentle breathing or a warm bath can help you relax.
- Put screens aside before bed. Bright light and stimulating content can make it harder to switch off.
- Watch the timing of stimulants and meals. Caffeine, nicotine, alcohol and a large late meal can interfere with sleep.
- Make room for regular movement. Choose activity you enjoy during the day; avoid vigorous late exercise if it leaves you feeling alert.
For more practical ideas, read our guide to sleep habits that can help you rest.
Dreamy sleep: making space to unwind
Stress can stand in the way of a good night's sleep. One approach is mindfulness meditation, which helps train your attention to return to the present rather than following every worry.
A trial involving 49 older adults with sleep disturbances compared a six-week mindfulness programme with sleep-hygiene education. The mindfulness group reported greater improvement in sleep quality. It was a small study in a particular group, rather than a guarantee that one meditation exercise will solve everyone's sleep problems.6
Try a short practice during the day or as part of winding down: notice your breathing without forcing it, and gently bring your attention back when your mind wanders. Our guide to coping with anxiety includes mindful senses and STOP exercises you can explore.
Nutritional and herbal options
Magnesium and your evening routine
Magnesium is found in foods such as nuts, spinach and wholemeal bread. A varied diet helps you meet your nutritional needs; waking during the night alone does not establish that you have a deficiency.7
A review of three small trials in older adults suggested magnesium might help with some insomnia measures, but the evidence was low to very low quality. The studies do not establish that a supplement increases deep sleep or REM sleep for everyone.8
If you are considering supplementation, compare the form, the amount of magnesium provided and the directions. You can explore our Magnesium Glycinate product and magnesium range to find an option that fits your nutritional routine.
Herbal help: valerian
There are also herbal options used to help with sleep. An earlier systematic review suggested valerian may improve reported sleep quality, but differences between studies and methodological limitations made firm conclusions difficult.9
Valerian SleepAid is a traditional herbal medicine used for the temporary relief of sleep disturbances caused by mild anxiety, based on traditional use only. Always read the leaflet and check that it is suitable for you.
Choose products for their intended use and follow their directions, rather than trying to force a particular sleep stage. A pharmacist can help if you take medicines or are unsure which option is suitable.
Can sleep trackers measure your sleep stages?
Sleep-tracking technology can help you notice bedtime patterns, but consumer devices estimate sleep using signals such as movement and heart rate. Their stage labels are not equivalent to the brain-wave measurements used in a clinical sleep study, and a reassuring score cannot rule out a sleep disorder.10
Use trends alongside how you feel during the day, rather than judging your sleep by one night's deep-sleep number.
When to seek support: speak to your GP if sleep problems have lasted for months or are making daily life hard to cope with. If someone notices your breathing stopping and starting, or you gasp or choke during sleep, ask about sleep apnoea rather than relying on a tracker.5, 11
For persistent insomnia, a GP may recommend cognitive behavioural therapy to address thoughts and behaviours that keep you awake. Treatment can be tailored to what is disrupting your rest.5
Sleep stages FAQs
Are there four or five stages of sleep?
The current model describes four: N1, N2, N3 and REM. Older descriptions split deep sleep into two stages, which is why you may still see references to five.
Is REM sleep the same as deep sleep?
No. Deep sleep is N3, a non-REM stage. REM has a different pattern of brain activity and is strongly associated with vivid dreaming. Both belong in a normal night's sleep.
How much deep sleep should I get?
There is no single nightly amount everyone should try to achieve. Deep sleep changes with age and across nights. Focus on allowing enough sleep overall, a regular routine and how rested you feel, rather than chasing a wearable's target.
Is every sleep cycle exactly 90 minutes?
No. Cycle length varies, and the balance of stages changes through the night. A 90-minute estimate can help explain the idea of cycles, but it is not a precise bedtime calculator.
Is it normal to wake between sleep cycles?
Brief awakenings can be normal. If you repeatedly struggle to return to sleep or feel very sleepy during the day, consider the wider pattern and seek advice if it continues.
How can I build a better bedtime routine?
Choose a regular wind-down time and one or two relaxing activities, such as reading, gentle breathing or a warm bath. Keep the bedroom dark and comfortable. Start with a routine you can repeat, then adjust it according to what helps you feel ready for sleep.
