Chronic insomnia: Why we lose sleep over it

So what is the difference between a poor run of sleep and the medical condition, insomnia?

"It's normal for everyone to have disrupted sleep sometimes," says Dr Anna Weighall, a lecturer in psychology at the University of Leeds.

"It becomes chronic when it's most nights, most weeks; when it's affecting interaction with family and friends, and your inability to carry out your job."Those who "chronically undersleep" - regularly sleeping less than 5 hours - "are more likely to suffer health problems, including weight gain, cardiovascular disease and diabetes," she adds.

According to the NHS, you may be suffering from insomnia if:

• Changing your sleeping habits hasn't worked

• You've had trouble sleeping for months

• Your insomnia is affecting your daily life in a way that makes it hard for you to cope

Typically, patients with insomnia are referred to a therapist for cognitive behavioural therapy - an eight-week course intended to help the patient "change the thoughts and behaviours that keep you from sleeping".

Ultimately, it may be a question of adapting your lifestyle: moving away from shift work or excessively late working.