"Thou art inclined to sleep. 'Tis a good dullness,
And give it way. I know thou canst not choose."
(Prospero to Miranda. The Tempest, William Shakespeare)
If you're a Shakespeare buff, you might think the magician Prospero was casting one of his spells when urging his daughter to yield to a feeling of daytime drowsiness. I prefer to think he was introducing her to the benefits of a voluntary afternoon nap; and that Shakespeare himself was one of napping's early fans. I'm a fan too; and my elder daughter, a doctor frequently working nights, thanks me for bequeathing her the ability to nap.
Famous people who've advocated napping are legion. On my side of the Atlantic, Sir Winston Churchill was my favourite exponent, writing: "Nature has not intended mankind to work from eight in the morning until midnight without that refreshment of blessed oblivion which, even if it only lasts twenty minutes, is sufficient to renew all the vital forces."
... and in the Cabinet War Rooms, Britain's wartime nerve-centre under Horse Guards Parade , you can see the bed in which he slept for an hour every afternoon during WWII. A routine he'd learned in his twenties served him well.
A later British Prime Minister, Margaret Thatcher, was famous for sleeping only three or four hours during the night. What is less well known is that she "did not like to be disturbed around 3pm".
Famous American nappers include former Presidents JFK, LBJ, Reagan and Clinton; and General Stonewall Jackson.
Talking of military leaders, last but definitely not least in my list is one of the most famous nappers of all: Napoleon. He could apparently nap just before - and even during - a battle.
Many studies endorse Churchill's statement. Napping has been shown to boost creativity, mood and productivity; and a one-hour nap improves alertness for up to ten hours.
Napping also reduces stress and thus reduces the risk of heart attack and stroke, diabetes and excessive weight gain. A University of Düsseldorf study found the onset of daytime sleep had memory benefits that remain effective even after naps of only a few minutes. Enlightened employers - Huffington Post is one of them - now recognise the benefits.
When to nap?
It depends on your schedule and your 'chronotype' i.e. whether you are a lark or an owl. In general, sometime between 1pm and 3pm is a period of maximum drowsiness for most people - irrespective of climate and of whether or not they've eaten; but we can be more precise thanks to a 'nap wheel' developed by sleep scientist Sara Mednick. It predicts that if you wake at seven, for example, the optimum time to nap would be around 2pm.
For how long?
It's a case of 'horses for courses.' US science writer Jennifer Ackerman summarised as follows:
• A 20-minute snooze can enhance alertness
• Limit the nap to 45 minutes if you need to spring into action on waking
• A 60-minute nap improves alertness for 10 hours
• Naps of 90-120 minutes encompass all stages of sleep and help clear the mind
A full sleep cycle typically lasts 90 - 100 minutes; two stages of light sleep, two of deep sleep, then an REM (rapid eye movement or dreaming) stage.
Waking from deep sleep (Stages 3 and 4) after 45-90 minutes can lead to sleep inertia. But after a nap including a full sleep cycle of 90-100 minutes, you wake refreshed from REM sleep.
Power naps and NASA
Not long ago, the US's National Transportation Safety Board called for 'controlled naps' to be built into night shifts. Referring to a 1995 study from NASA, which he co-authored, NTSB member and fatigue expert Mark Rosekind said that a 26-minute nap would improve performance by 34% and alertness by 54%.
Some experts, however, feel 26 minutes is too long for a genuine 'power-nap,' as it risks going into deeper sleep. Naps of twenty minutes or less are mostly of light sleep; waking then, you're more likely to feel refreshed.
Interrupted naps, scheduled naps
One of the most universal benefits is the effect on memory. Harvard Medical School research found that napping, especially if including REM sleep, was an effective tool for improving memory and learning ability.
Even better, you may get the benefits even if your nap is interrupted. A 2008 study showed that the onset of sleep may trigger active memory processes that remain effective even if sleep is limited to only a few minutes.
Even knowing that a nap is coming can actually reduce blood pressure, it is claimed; so simply scheduling a nap is a worthwhile stress-relief strategy.
- Minimise noise and light, of course; and keep warm. (I personally can't fall asleep if my feet are cold.)
- Lie down: you'll take 50% longer to fall asleep in a sitting position.
- Finally, clear the mind of 'chatter' by focusing on your breathing. Learning to relax muscle-groups in turn, or meditation or visualisation techniques, can be helpful.
Churchill and JFK probably didn't know much about sleep science; they just did what they knew worked for them. We're not all national leaders, so we might face resistance from colleagues. The solution: work for an enlightened employer - or for yourself - then find for yourself the benefits of an afternoon nap.
Want to know more?
Sara Mednick's Nap Wheel
The NASA Nap
Jennifer Ackerman's Sex-Sleep-Eat-Drink-Dream