So should we discourage naps in preschool children – even if they really seem to need one?
Short naps have also been shown to be good for adults – improving alertness and reaction times.
It found that children who missed their naps slept better at night and scored higher in studies of memory and attention.
Related: Sleeping pods for students: can naps replace a good night's sleep?
"This #RebelHeart had a dream," she tweeted, presumably between naps in the middle of the afternoon.
Prajesh Patel, 20, an economics student at Queen Mary, University of London, takes power naps consistently and is a fan of this technique.
And naps have to be a good thing for preschoolers, surely, since they need to unwind and get enough sleep for their brains to develop?
Children vary in how quickly their daily cycle of waking and sleeping becomes consolidated into one chunk at night – afternoon naps generally decline between the ages of three and five.
Also, the authors of the review article are clear that the research on children's naps is of poor quality: some studies rely on parents remembering how much their children slept, or were for very short periods.
The study also found that the children who went without naps did not sleep more at weekends.
Day one was spent at sea, cruising shorthand for spa treatments, long lunches, reading and naps.
