Seven hours of sleep per night is optimal in middle to older age, study suggests

The data indicated seven hours of sleep per night was the optimal amount for cognitive performance

The researchers say one possible reason for the association between insufficient sleep and cognitive decline may be due to the disruption of slow-wave — 'deep' — sleep. Picture: Alamy/PA

Seven hours of sleep per night is the ideal amount in middle to older age, a study has suggested.

Both too much and too little sleep are associated with poorer cognitive performance and mental health, according to researchers from Cambridge University and Fudan University in China.