From smartphones that monitor REM to ever-changing “sleep hygiene” rules, we all know a good night’s sleep is essential to wellbeing. Advice varies, however, on how long actually constitutes that restorative rest.
Margaret Thatcher famously got by on four hours, while the accepted standard is eight. I prefer nine - but according to a major new study, we should all be aiming for exactly seven hours’ sleep, from our thirties to old age.
