While overnight sleep is our richest source of rejuvenation, napping offers a bite-size portion of its benefits. “After 5-10 minutes you enter stage-two sleep, which is when electrical brainwaves show information starting to move from our small working memory centre, the hippocampus, into our larger memory-storing cortex,” explains Dr Sophie Bostock, founder of The Sleep Scientist. “Within as little as 10-20 minutes of napping, you get improvements in learning and focus.”
   
“A systematic review found afternoon naps had small-to-medium benefits over multiple cognitive tests, including memory, executive function and processing speed,” she adds. “What’s especially interesting is that this applies regardless of age, whether you’re a regular and occasional napper, or how well you slept the night before. Potentially, we’re all able to benefit from a short nap.
   
It’s not just a power nap for the brain, either. “Short napping boosts mood and may improve cardiovascular health and immunity, as well,” adds Dr Browning. With studies linking 40 winks to a reduced risk of heart attack and stroke, a siesta has never sounded more agreeable.

Short, regular naps are good for us, but be vigilant if you’re suddenly desperate for daytime dozes, says Dr Bostock. “A common cause is sleep apnoea, when you have pauses in breathing overnight. You’re constantly waking into lighter sleep so you’re only getting a fraction of the quality rest you would normally. As well as causing daytime tiredness, sleep apnoea increases the risk of heart disease, diabetes and depression, so see your GP, especially if you’re waking gasping for breath.”

Ideally, lie down. “It’s easier for your mind and body to relax when you’re not supporting your postural muscles,” says Dr Bostock. Snuggling under your own duvet is Dr Browning’s recommendation, but Dr Bostock says this can potentially backfire: “We want to maintain a positive relationship between your bed and long sleeps.” So experiment; a power nap on the sofa might work best for you.
 
Eye masks, ear plugs and white-noise apps are useful for blocking physical distractions, while familiar props – such as a blanket or scent spray – may get you in the zone faster. “Anything you do regularly in a pre-nap routine can be a helpful signal to your brain,” says Dr Browning.
 
If you’re at work, go to your car and recline the seat, or find an empty meeting room. “Airport travel pillows aren’t great, but you can try lean-on desk pillows,” says Dr Browning.

There’s a time and place for everything, and napping is no exception. “The ideal is a power nap after lunch, when we have a natural circadian dip. For optimum benefits, napping should be finished by 3pm and last around 20 minutes, so it won’t impact night-time sleep,” says Dr Browning. “You’ll wake from light sleep, so you’ll feel energised.”
 
“If you have a longer nap, say 40-60 minutes, you’ll wake from deeper sleep with the groggy feeling of sleep inertia, when your body is desperate to finish the sleep cycle,” she adds. Should you need to nap for longer, 90 minutes is far more restorative. “That’s just your full sleep cycle, meaning you’ll wake up feeling good.”
 
Sadly, office napping – of any length – is usually frowned upon, but you can try a 20-minute post-work snooze, instead. “It’s unlikely to affect night-time sleep,” says Dr Bostock. “But keep a sleep diary to assess it.”

Ask why you’re low on sleep time. “Napping can be a helpful top-up if your lifestyle prevents you getting enough at night; for instance, if you’re a shift worker or have a baby,” says Dr Browning. “However, if it’s because you’re tossing and turning, napping is just perpetuating the problem.”
 
Even if you go through a full sleep cycle, daytime naps are of lower quality than night-time sleep: “It’s because your body clock is programmed to sleep overnight,” says Dr Bostock. “Also, unlike a quick snooze, long daytime naps stop you building up ‘sleep pressure’ for bedtime. You’ll find it harder to nod off and may have more broken sleep.”

Waking up is as important as falling asleep. “Always set an alarm so you won’t nap for too long,” says Dr Bostock. “It's common to take 10 minutes to fall asleep, so build in that time to relax.” Pick your alarm carefully, too, advises Dr Browning. “If you set an abrasive-sounding alert, you’ll go from a relaxing nap to a racing heart and a flood of adrenaline. Waking up gently, to a softer sound with a gradually increasing tone, is much better.”
 
Then get up immediately, resist the temptation to hit snooze (it’s what Dr Browning calls “the junk food of sleep”) and enjoy your uplift in energy. The dream life…

Lynne Hyland is Senior Beauty Editor at “Good Housekeeping”