These days I often hear people bragging about how little they sleep. It is as though sleep is a bad thing and that having as little of it as possible is clever1. It will, perhaps, seem clever to people who sleep less precisely because of what sleeping less does to a person: in one phrase, it cripples our ability to think clearly. Sleeping less is neither a sign of good health nor an indicator of cleverness and success.
More importantly, it must be noted that I am, and have long been, of the opinion that sleeping is a waste of time because, if we could somehow go without sleeping, we could use that time productively for something else. But never have I argued that sleep is a bad thing and that we must limit it severely. There is a difference between something being unnecessary and something being a waste of time: if something is unnecessary, it is certainly a waste of time; but if something is a waste of time, it may yet turn out to be necessary.
The Atlantic published a wonderful article by James Hamblin on this topic a few months ago titled How to sleep. It drew on Dr Hamblin’s own experience working overtime as a resident doctor. He talks, at one point, about a military-led sleep deprivation experiment that carries a tone, and yielded results, similar to a number of other experiments of its type—
Around the (1960s) the U.S. military got interested in sleep-deprivation research: Could soldiers be trained to function in sustained warfare with very little sleep? The original studies seemed to say yes. But when the military put soldiers in a lab to make certain they stayed awake, performance suffered … (But) they couldn’t tell that they had a deficit.
“They would insist that they were fine,” said Dinges(^ David Dinges, chief of the division of sleep and chronobiology at the University of Pennsylvania.), “but weren’t performing well at all, and the discrepancy was extreme.”
… In one study published in the journal Sleep, researchers kept people just slightly sleep deprived — allowing them only six hours to sleep each night — and watched the subjects’ performance on cognitive tests plummet. The crucial finding was that throughout their time in the study, the sixers thought they were functioning perfectly well.
Effective sleep habits, like many things, seem to come back to self-awareness.
It is the last sentence in that excerpt that, I think, sums up the entire article: often people who sleep less are under the false impression that they are perfectly alright while objective assessment clearly shows otherwise. This is likely what prompts people who look at sleeping less as an issue of prestige to claim that they are on the right track.
Getting seven hours of sleep in a twenty-four-hour day has been suggested by quite a few scientific studies as the sweet spot. However, it is the lower end of a range they advise; adults, as Dr E.J. Olson of the Mayo Clinic puts it, ideally need seven to nine hours of sleep. Other studies offer a broader range going from six to ten hours per day.
While, on the one hand, insufficient sleep can have negative effects most aptly summed as a ‘drop in performance’, sleeping too much is also a bad thing. A majority of studies tend to favour seven hours with some going so far as to claim that nine hours is too much2. In any case, anything above ten hours is enough sleep to substantially increase the risk of depression, diabetes, heart disease and generally lower a person’s lifespan.
Sleep requirements, therefore, are a trick grey area to say the least. Too little sleep can be bad as can too much of it.
Einstein is known to have slept ten hours every night besides napping during the day for twenty minutes or so. Beethoven is said to have slept from ten to six, punctually. Ironically, these two are examples of normal humans in this case. There is a rare breed of so-called short sleepers who are capable of surviving on as little as four hours a day. Nikola Tesla and Leonardo da Vinci are both said to have slept for only a handful of hours each day. Notably, Benjamin Franklin, who famously said, ‘Early to bed and early to rise makes a man healthy, wealthy and wise’, slept six hours a day.
The idea of sleeping in short bursts, like Leonardo, is called polyphasic sleeping. Such people practise sleeping several times a day for anywhere from five to twenty minutes each time, totalling about four or five hours a day. The more commonly seen practice is that of sleeping twice a day, once at night and again in the afternoon, which is called biphasic sleeping. The United States Air Force Research Laboratory itself states a requirement of eight hours of sleep per day for its troops to ‘maintain top-notch performance’.
One of my favourite composers is Mozart, whose sleep patterns have been well documented in his own letters and show a particularly interesting fluctuation3. He was twenty-one, unemployed, living with the Weber family and making money teaching others to play instruments when he wrote the following letter to his father:
I am writing this at eleven at night, because I have no other leisure time. We cannot very well rise before eight o’clock, for in our rooms (on the ground-floor) it is not light till half-past eight.
It is reasonable to assume that that routine would give him a good seven hours of sleep or more. However, five years later, in a letter to his sister, Mozart writes of a different routine that affords him only five hours of sleep a day:
At six o’clock in the morning I have my hair dressed, and have finished my toilet by seven o’clock. I write till nine. From nine to one I give lessons. I then dine, unless I am invited out, when dinner is usually at two o’clock, sometimes at three … I cannot rely on my evening writing, so it is my custom (especially when I come home early) to write for a time before going to bed. I often sit up writing till one, and rise again at six.
This would imply a five-hour sleep routine, but only because Mozart could not afford any more sleep; he never claims, at any point, that sleeping less helped him compose. However, unlike Mozart, since most claims about Leonardo or Tesla can hardly be accurately confirmed, with most accounts likely having been exaggerated over the years, the sleep habits of successful people living in our own times are, arguably, a better topic of discussion.
Forbes reported on this a little over a year ago in an article by Alice Walton titled ‘The sleep habits of highly successful people’. The article talks about how much sleep a person needs and examines the sleep schedules of successful CEOs, former presidents etc. citing an interesting infographic4 that, interestingly, claims that Microsoft co-founder and former CEO Bill Gates sleeps seven hours a day, which happens to be the same as Twitter’s Jack Dorsey, Apple’s Tim Cook, and Amazon’s Jeff Bezos.
Arguing that clever people sleep less is clearly unfounded5. In fact, working more is what makes people successful, not sleeping less. And saying that you sleep less by no means suggests that you work more when you are awake. Perhaps the reason why some (not all, not even most) famous, successful people ended up sleeping less is because they were working a lot, not because sleeping less was a great thing.
It does, then, really come down to what an individual needs: some people can do with less sleep, about five to six hours a day, while others need seven to eight hours, whether in one go or two. And sleep itself is not related to success in anyway. Indeed if you think so, you should probably sleep more because insufficient sleep might be disturbing your reasoning.
This article was prompted by two things: my own assessment of my sleep pattern (on average, I sleep six-and-a-half hours a day, from 22:30 to 05:00) and an increase in the number of people I hear claiming to be clever as a result of hardly sleeping at all. ↩︎
This is, possibly, an effect of there not being sufficient research on sleep and its effects. ↩︎
I recommend reading Maria Popova’s article ‘Mozart’s daily routine’ on her wonderful website, Brain Pickings, for more commentary about Mozart’s day. ↩︎
The exact source of the data used in the infographic is uncertain, so I would suggest taking it with a grain of salt. ↩︎
Claiming that people who sleep less are clever is even worse. ↩︎