Sleep Stages and Their Function
| Stage | Duration | Key Function |
|---|---|---|
| NREM Stage 1 (Light sleep) | 1–7 min per cycle | Transition to sleep, hypnic jerks |
| NREM Stage 2 | 10–25 min | Memory consolidation, temperature drop |
| NREM Stage 3 (Deep/slow-wave) | 20–40 min | Physical repair, immune function, growth hormone |
| REM sleep | 10–60 min (longer later) | Emotional processing, dreaming, memory consolidation |
Sleep Hygiene — Evidence-Based Strategies
- Maintain a consistent sleep/wake schedule — even weekends
- Keep bedroom cool (16–18 °C), dark, and quiet
- Avoid screens (blue light) 1 hour before bed
- Avoid caffeine after 2pm (half-life ~5–6 hours)
- Avoid alcohol — it fragments sleep architecture despite helping you fall asleep
- Exercise daily — but not within 3 hours of bedtime
- Use the bed only for sleep and sex — not work or screens (stimulus control)
- If awake for >20 minutes, get up and do something calm until sleepy
CBT-I First LineCognitive Behavioural Therapy for Insomnia (CBT-I) is more effective and longer-lasting than sleeping tablets for chronic insomnia. Available as guided apps (Sleepio), online programmes, or with a therapist.
What is sleep apnoea?
A condition where the airway repeatedly collapses during sleep, causing brief arousals and oxygen drops. Signs: snoring, gasping, unrefreshing sleep, daytime sleepiness, morning headaches. Diagnosed by a sleep study; treated with CPAP.
Can melatonin help with insomnia?
Melatonin is most effective for circadian rhythm disorders (jet lag, shift work). For chronic insomnia, it has a weaker effect than CBT-I. It's available over-the-counter in some countries.
How much sleep do teenagers need?
Teenagers need 8–10 hours. Their circadian rhythm naturally shifts later, making early school times biologically difficult. This is a physiological pattern, not laziness.
When does insomnia need medical attention?
If poor sleep has persisted for more than 4 weeks, is significantly affecting daily functioning, or is accompanied by symptoms of depression, anxiety, restless legs, or sleep apnoea — see your GP.
Medical Disclaimer: This page is for general education only and does not replace professional medical advice. Always consult a qualified healthcare provider.