Who knows about sleep? Astronauts. They have to. Their bodies are cut off from many of the normal external cues that remind us what time it is.
In orbit they can experience a dozen sunrises and sunsets a day which makes their circadian rhythm go completely haywire. When you're in a tin can floating through the cold darkness of outer space, being off your game due to lousy sleep can have very bad results. When sleep deprivation has you so messed up you don't notice you're taking photos of the walls instead of Earth, yeah, that could present a problem.
Cosmonaut Valentin Lebedev reported in his diary that he had a tendency to make mistakes on days following an unusually late bedtime; on one occasion he took 50 Earth-observation photographs through a closed porthole before realizing his error. [Bold Endeavors: Lessons from Polar and Space Exploration]
So NASA started doing some serious research. They quickly realized a few things:
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Without light, darkness, and other contextual signals, your ability to regulate sleep times can be a mess.
Lacking the normal circadian cues of daylight and darkness, individuals, when permitted, tend to become desynchronized; that is, they retire to bed at a later hour and remain awake longer each night. [Bold Endeavors: Lessons from Polar and Space Exploration]
2. Your body doesn't naturally stay on a 24-hour cycle
Without something to rein it in, you'll work off a 25.4-hour day. This drift compounds and eventually your sleep cycle can totally spin out of control.
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If the individual is isolated without access to any time cues, however, the sleep/wake cycle and body temperature rhythms drift toward later times each day and are expressed in free-running periods of 25.4 hours; at this rate an individual's sleep/wake cycle could drift nearly 10 hours per week in the absence of diurnal cues… In extreme cases, an individual can cycle completely around the clock. [Bold Endeavors: Lessons from Polar and Space Exploration]
3. You're not very good at judging sleepquality
You may think sleeping with the lights on doesn't affect you, but it does. And you won't necessarily notice your reduced performance the next day, either.
…it is a folklore belief that all people adapt to regular sounds and are not affected by noises perceived during their sleep. In fact, the sleep of most people is disturbed by even the most regular sounds; for some individuals, the quality of sleep can be reduced without conscious recognition or complete awakening. [Bold Endeavors: Lessons from Polar and Space Exploration]
Today our bodies have become thoroughly confused by the artificial signals of modern life. Light is no longer a cyclical function of the sun, but of always-on indoor lights, TV screens, and computer monitors. Temperature no longer follows a dynamic cycle of cooling at night and warming during the day but sits at a static level set by the thermostat. Human chatter and social interaction used to follow a natural ebb and flow, but now we are more likely to live and sleep in isolation from real people, even while we have 24/7 access to artificial people (faces on TV, voices on the radio). Then, after utterly confusing our circadian rhythm, we try to take back control with stimulants (caffeine, nicotine) and depressants (alcohol, sleeping pills). Is it any wonder that a third of Americans are chronically sleep-deprived? [The Paleo Manifesto: Ancient Wisdom for Lifelong Health]
Maybe you think this doesn't affect you — or at least not much. You're wrong. Remember #3 above. Research done on non-astronauts has shown the same thing. After two weeks of six hours of sleep a night, you're legally drunk:
…by the end of two weeks, the six-hour sleepers were as impaired as those who, in another Dinges study, had been sleep-deprived for 24 hours straight — the cognitive equivalent of being legally drunk.
But what did the chronically sleep deprived say when asked how they felt? It's not affecting me. Even 14 days into the study, they said sleepiness was not affecting them. In fact, their performance had tanked. In other words, the sleep-deprived among us are lousy judges of our own sleep needs. We are not nearly as sharp as we think we are.
So if you are having reduced performance due to sleep issues, you may not be aware. This is a problem. So what answers did NASA come up with?
What you need to do
In the past I've rounded up sleep research and documented my own sleep-hacking experiments. Let's add some astronaut knowledge. Given you probably don't have to deal with the thruster jets of Skylab waking you up or the sounds of the hull of your ship expanding and contracting, I've edited the recommendations down to four points:
Maintain a consistent schedule, even on weekends. Keep in mind the "free-running" problem. Your body will push later if given the chance.
Take an hour to wind down before bed. Yes, you're busy. But your time is not more precious than an astronaut's. So take the time to wind down.
If you don't have strong day/night cues, add them. Get sunlight in the morning. Dim the lights at night. Turn electronics off as bedtime approaches or use an application like f.lux.
Keep your bedroom dark, cool, and free from noise. Even if you think "the light doesn't bother you" or "the noise isn't that bad" it can still reduce sleep quality.
A useful technique is setting an alarm clock — not to wake up, but to get ready for bed. Set an alarm for an hour before bedtime. When it goes off, finish up any work on the computer, turn off the TV, turn off any unnecessary lights, and start to wind down for the day. [The Paleo Manifesto: Ancient Wisdom for Lifelong Health]
This prevents you from cheating yourself on sleep and allows you to wake up naturally. (Even if "naturally" happens to be on the surface of the moon.)
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