Irish Examiner View: To sleep, perchance to dream — for seven hours only

Shakespeare was really on to something when he wrote: “Sleep, the main course in life’s feast, and the most nourishing.”

According to a new study, seven hours is the optimum amount of time for adults aged 38 to 73. File Picture

What is the difference between too little and too much? It is one of life’s imponderable questions, but the answer has come a little closer, at least in terms of the subject of sleep, following a survey of half a million adults.

Scientists, writing in the journal Nature Aging, warn that “too little or too much sleep” is likely to cause cognitive problems in the long term and that the optimum dose is seven hours for people who want to keep their minds healthy in middle age and beyond. 

Cambridge University researchers examined data from nearly 500,000 adults, aged 38 to 73, who took part in the British Biobank project, a study that monitors sleeping patterns, mental health, and wellbeing, as well as intellectual activity. Insufficient and excessive sleep were associated with slower processing speed and poorer visual attention, memory, and problem-solving skills.

Sleep patterns vary from person to person, with the average individual on an average night cycling through four stages. Researchers say stage-three slow-wave ‘deep’ sleep is particularly important in consolidating memories and allowing for growth, physical recovery, and boosting the immune system. Previous studies associate interrupted sleep with increased inflammation, indicating a susceptibility to age-related diseases in older people.

It was Shakespeare in Macbeth who wrote: “Sleep, the main course in life’s feast, and the most nourishing.” And given that the central plot of the play involves the night terrors, he was clearly onto something, 416 years ago.

So the advice must be to turn to your partners and friends from now on and tell them firmly: “Time for me to get my head down. See you in seven hours.”