If You Snooze, You Lose
Jim Horne argues we get plenty of sleep:
The apparent desire for more shut-eye, together with oft-repeated assertions that our grandparents slept longer, all too easily leads to the conclusion that we in the west are chronically sleep-deprived. … [Such] Claims … are nothing new – in 1894, the British Medical Journal ran an editorial warning that the "hurry and excitement" of modern life was leading to an epidemic of insomnia. …
Over the past 40 years, there have been several large studies of how much sleep people actually get, and the findings have consistently shown that healthy adults sleep 7 to 7.5 hours a night. The well-known "fact" that people used to sleep around 9 hours a night is a myth. …
Support for today’s epidemic of sleep debt supposedly comes from laboratory studies using very sensitive tests of sleepiness … in which participants are sent to a quiet, dimly lit bedroom and instructed to "relax, close your eyes and try to go to sleep". These tests … are able to eke out the very last quantum of sleepiness which, under everyday conditions, is largely unnoticeable.
Another line of evidence trotted out for chronic sleep deprivation is that we typically sleep longer on vacation and at weekends, often up to 9 or 10 hours a night. … We enthusiastically eat and drink well beyond our biological needs. Why shouldn’t it be the same with sleep? Most mammals will sleep for longer than normal if overfed, caged or bored. The three-toed sloth … kept in zoos sleep around 16 hours a day – yet in their natural, wild state they sleep less than 10. …
What of the risk of a sleep shortage causing obesity? Several studies have found a link, … The hazard … only becomes apparent when habitual sleep is below 5 hours a day, … [who] would only gain a kilogram or so of fat per year. … People sleeping more than 9 hours a night are just as likely as short-sleepers to be fat. …
My team recently investigated these questions by giving around 11,000 adults a questionnaire … The people with a sleep deficit were no more likely to experience daytime sleepiness than those without. … We then asked, "If you had an extra hour a day, how would you prefer to spend it?" … Only a handful of people opted to use their extra hour for sleep.
Here's another report on the dangers of driving while tired. It's about a controlled experiment which avoids the problems Zubon worries about, but doesn't tell us how much harm results.
There are plenty of alternatives to coffee for getting caffeine. My favorites are Rocket Chocolate, and Penguin caffeinated mints.
Drowsy driving is hard to pin down. The crash data is horrible, because by the time the officer arrives to fill out the report, the driver is awake (or dead, or in an ambulance). Loud crashing sounds can do that. There is an interaction effect between drowsiness and alcohol, such that two beers and sleep deprivation might work out to four beers, but again try getting good data since most drinking happens at night. When the bars close at 2am, people are not getting much sleepier or drunker than that.
The evening rush hour is worse for crashes than the morning, but there are many possible explanations. It seems intuitive that in the morning you are both rested and caffeinated, so you have fewer drowsiness-related crashes, but I cannot support that with reliable data. All I can do is recommend an extra cup of coffee around 4pm. And I don't drink coffee, so that's out.
Friday evening rush hour is worse for crashes than the earlier days of the week, but again that is not just drowsiness. I would like to be able to tell a clear story about mounting sleep deprivation, with people becoming increasingly tired as the week wears on and sleep debt builds up, but I would want to see a steady increase in crashes as the week wears on. Running numbers quickly for my state, it seems to follow that trend, but Thursday is not cooperating. It is closer if I drop back a year or two (but not three). I might be able to find a better connection if I spend more than a few minutes, but it will remain shaky because we cannot test for "drowsy" after the fact as easily as "drunk."