Dr Kirstie Anderson told The Irish Times that sleep is vital for maintaining normal immune function; recovering from muscle damage, for example, after exercise; ensuring your cells divide normally; consolidating memory; enhancing mental health; and helping to regulate temperature, weight and appetite.

“And it’s worth remembering,” she adds, “that the total amount of sleep we require changes as we age, with the average adult over 45 years needing about seven rather than eight hours of sleep.”