The misery of insomnia is usually compounded by worry about the dangers of getting too little sleep. We hardly fret about getting too much — as if! But a new study from researchers at Washington University School of Medicine, Missouri, which monitored 100 adults in their mid to late seventies over several years, apparently found an association between less than five and a half hours’ sleep or, rather astonishingly, more than seven and a half hours and declining cognitive performance. The “sweet spot”, where cognitive function remained stable, was in “the middle range” (ie 5.5-7.5 hours) of total sleep time.
So should those who until now have felt smug about reaching the holy grail of eight hours be concerned? Are we, the well rested,