Short nights naturally lead to daytime doziness

SIR – Flic Everett’s piece on the optimal amount of sleep (Features, June 13) repeats Margaret Thatcher’s claim that she managed to function with only four hours of it. Napoleon had a similar reputation.

Sleep of such short duration will necessarily lead to excessive daytime sleepiness. There are numerous photos of the Iron Lady asleep at her desk, and the French painter

Anne-louis Girodet made sketches of Napoleon asleep in the theatre.

The relationship between daytime tiredness and accidents at home, on the road or at work is compelling, and although it cannot be claimed that accidents will necessarily follow a sub-optimal sleep time, there is sufficient cause for concern. Professor Emeritus Ian Hindmarch Walmer, Kent

Forty winks: Reading, by the American Impressionist Frederick Childe Hassam (1859-1935)