- CBT-I
- Cognitive behavioural therapy for insomnia: a structured approach to sleep-related thoughts and behaviours. It is more than a list of bedtime habits and should be adapted to the person.
- Circadian rhythm
- The body’s roughly 24-hour timing pattern, which helps coordinate sleep and wakefulness. Light, darkness and daily routines influence this internal clock.
- Daytime sleepiness
- A tendency to feel sleepy or fall asleep during waking hours. It can affect driving and other activities, and persistent sleepiness may need assessment.
- Insomnia
- Recurring difficulty falling asleep, staying asleep or getting restful sleep.
- Long-term insomnia
- Sleep difficulties that continue for three months or longer.
- Short-term insomnia
- Sleep difficulties lasting less than three months.
- Sleep apnoea
- A condition in which breathing repeatedly stops and starts during sleep. Loud snoring, gasping or marked daytime tiredness are reasons to discuss assessment with a GP.
- Sleep diary
- A record of sleep times, awakenings and daytime habits to help describe your sleep pattern.
- Sleep hygiene
- Everyday habits and bedroom conditions that support sleep.
- Sleep latency
- The time between trying to fall asleep and falling asleep. It is one way to describe a sleep pattern; it does not diagnose a condition by itself.
- Wind-down routine
- A regular period of quieter activity before bed.
Sources & further reading
General information to help you prepare questions for a healthcare professional. Source pages checked on 1 November 2026.
