Rocket Fuel


Sleeping in Outer Space – Zero Gravity Sleep

Nov 2, 2015 By Reverie Staff
night sky

Some of us have dreams that we’re in outer space or on faraway planets. Others are actually in outer space or on faraway planets when they dream. It’s not an element of space travel that gets much press, but sleep in space is an inevitability for astronauts who spend months (or over a year!) at a time away from planet Earth. And, like most things that happen in outer space, zero gravity sleep is pretty darn fascinating.

Dude, Where’s My Bed?

You may not realize it, but gravity plays a huge role in your nightly slumber. You know that feeling of sinking into your mattress at the end of a long day? Made possible by gravity. A thick, heavy blanket comforting you with its weight? Yeah, that’s gravity too. And how about just staying in your bed all night long? You got it: gravity.

Astronauts in outer space, on the other hand, sleep while experiencing what’s called “microgravity,” or the condition in which people or objects appear to be weightless. They, and everything around them, are constantly floating, which means it’s impossible to lie down on a bed—both the astronaut, and the mattress, will be on opposite sides of the room in minutes. Equally impossible is resting your head on a pillow or snuggling under a blanket. Basically, nothing will stay in contact with you for long, unless you’re attached.

Which explains why a lot of astronauts attempt to replicate sleep on Earth by strapping themselves into chairs or attaching sleeping bags to walls when it’s bedtime. Some even secure their arms and legs to prevent limbs from hovering awkwardly all night, or smacking themselves in the face.

There’s also the question of your favorite sleeping position. If you like to curl up, you may be out of luck. You’re being pulled in every direction simultaneously, so try as you might to stay in your little fetal curl, you’ll soon be stretched out. To prevent this, some astronauts use a Velcro strap to hold their knees in place!

Add to all of that the fact that constant loud noises are a fact of life on spacecrafts and space stations, and that being in orbit dramatically disrupts your circadian rhythms, and it’s not surprising that astronauts average 30 to 60 minutes less sleep in space than they were getting on Earth.

Under (No) Pressure

But zero gravity sleep isn’t all bad. In fact, once you adjust to it, the benefits of weightless sleep are nontrivial. To understand why, just think about the aches and pains you’ve experienced after sleeping on a subpar mattress or contorting yourself into an awkward position during the night: all of those issues stem from pressure being applied with too much force to the wrong parts of your body. In space, there’s no pressure. As astronaut-turned-YouTube sensation Chris Hadfield says, “in space, you don’t even have to hold your head up, so you can relax every muscle in your body.” Astronaut Dan Barry, who has spent 30 nights in space on three different space missions, agrees. “Sleeping in space is fantastic!” He told NPR. “You just float…it’s perfect.”

Perhaps because of the complete lack of stress placed on the body during zero gravity sleep, the sleep itself has actually been shown to be more restful than sleep on Earth. At the 1960 Symposium on Physical and Biological Phenomena Under Zero G Conditions, Dr. Raphael B. Levine presented a paper asserting that two hours of sleep under zero gravity conditions is effectively equivalent to eight hours of “normal” sleep.

Coming Back to Earth

It wasn’t long before industry swooped in to capitalize on the physiological benefits of weightless sleep. As far back as 1963, scientifically-inclined entrepreneurs were developing innovations to replicate zero-g sleep, with inventions like the Aquarest, in which a person lies suspended in a solution of 10% sea salt to reap the benefits of weightlessness. Zero gravity beds were soon to follow, with bed and luxury mattress manufacturers designing products that simulate the completely stress and pressure free experience of sleeping in space.

Of course, the closest most of us will get to a zero gravity sleeping experience is having our blanket “float” away to our partner’s side of the bed. But if having our pillows stay under our heads all night is the consolation prize—we’ll take it.