Sleep becomes easier to understand when you separate two influences: sleep pressure, which generally rises while you are awake, and the body clock, which changes your tendency to sleep across the day. These are useful models, not a complete explanation of every poor night.

This course is for adult sleep habits. See a GP if changing habits has not helped, sleep problems have lasted months, or they make daily life hard to cope with. Also seek assessment for frequent daytime dozing, sleepiness affecting your life, or gasping, choking or pauses in breathing during sleep. Do not wait to finish a diary first.

Do not drive when sleepy. The NHS insomnia guidance (opens in a new tab) explains assessment and treatment, which can include cognitive behavioural therapy. We will not prescribe sleep restriction, medicines or treatment for a sleep disorder.