The secret seven

Seven hours’ shut-eye is the ideal amount of sleep for people of middle age and older to keep the brain functioning well, according to a new research study.

University of Cambridge scientists examined data from half a million people and found those enjoying this quantity each night had optimal cognitive performance and good mental health.

But too little and too much were associated with impaired cognitive performance, such as processing speed, visual attention, memory and problem-solving skills.

Lack of rest or oversleeping were also linked to symptoms of anxiety and depression, as well as worse overall wellbeing.