# Why do people in Cryogenic sleep not wear clothes?

In a lot of science-fiction stories, there are people who hibernate of sorts in cryosleep. Basically something like the person's body is stored in a container which is then chilled at really really low temperatures so that they can wake up at a much later date. Disregarding whether the person could have actually survived, why do they go to cryogenic sleep without clothes?

In most scenes where a person wakes up from cryogenic sleep, they are depicted without clothing. Is this because the clothing could be destroyed by the extremely low temperatures or some other reason? If it can preserve a human body so that he/she can wake up at a later date, it should be possible to preserve clothing right?

• Frozen people have anti freeze liquids injected in their body so ice crystals don't open them apart, clothes don't have blood that can keep the anti freeze liquid still so clothes will simply freeze and become like blades that could cut and slice the hibernated person cause any soft material becomes like broken glass when frozen. I suggest watching some videos about Alcor Spa and see how they do it. – user24999 Sep 12 '16 at 12:14
• In all the movies I can think of, the cryo-sleeping passengers are wearing some kind of futuristic full body suit - I can't think of a single one where they're naked. – Nathaniel Sep 12 '16 at 14:07
• If you're frozen for years, how do you know what's going to be in fashion when you get out? Better to go in naked and pick a new outfit afterwards. After all, if you're going for cryo then you're all about the cool, right? – Graham Sep 12 '16 at 14:49
• I can think of a couple movies on both sides. Movies are bad data source. The choice there is likely driven by desire to either avoid R ratings or (opposite) to eroticize, probably not science. – SRM - Reinstate Monica Sep 12 '16 at 14:57
• Why do some people wear, or not wear, clothes for normal sleep? It's probably purely cultural, and as @SRM says, in movies is probably driven by the director/producer's desired rating. – jamesqf Sep 12 '16 at 17:45

Cryo sleep is a medical procedure. Most full-body medical procedures are performed on nude subjects, even today. Reasons are numerous:

1. In case of emergency, you need ready access to various parts of human body, and you need it now.
2. It's easier to control bedsores without clothing.
3. For long procedures, you need catheters in urethra, anus etc, so not much left to hide anyway.
4. Less things you need to keep sterile.
5. Probably many more I don't know...

Now, for cryo, cooling rate and hardness of frozen fabric may be a factor, too. But given that full body anesthesia is routinely administered to naked subjects now, it's quite possible no one would even consider changing that.

• If the liquids in a person's body were actually frozen, I don't think bedsores wouldn't be a problem. If, however, the temperature was such that the liquids remained liquid but metabolism was reduced to a minimal rate, the first problem I could think of would be similar to bedsores but slightly different: the skin attaching itself to the clothing over a period of decades or centuries. – supercat Sep 12 '16 at 13:58
• @supercat if freezing and unfreezing would take long enough time, they might. Also, some abrasive damage might occur. but that's not the point of my answer, really. the point is docs might never reconsider today's practices at all. – Mołot Sep 12 '16 at 14:01
• Bedsores from clothing are probably the biggest issue, especially if the clothing is anything that can get even a tiny wrinkle. – arp Sep 13 '16 at 15:48
• > If the liquids in a person's body were actually frozen < At least in theory liquid in body should be replaced or diluted with something to prevent freezing, because frozen liquid tears up the cells and there is no way back to fix it. – Ski Sep 16 '16 at 9:49

The cooling rate, especially around the freezing point of water, needs to be controlled carefully in order to not cause damaging crystal growth. Wearing clothing makes the rate of cooling more unpredictable, so it introduces more risk.

If any clothing is used, it will be special outfits whose isolation properties are well known and thoroughly tested.

• also, clothes might additionally complicate the thawing process (different parts get heated differently, and you wouldn't want a fully thawed brain with a half-frozen heart) – hoffmale Sep 12 '16 at 13:50
• Re special outfits - I would much prefer a blue skintight jumpsuit with yellow stripes over a bare behind. – John Dvorak Sep 12 '16 at 15:28
• @JanDvorak - we can't all be vault dwellers... – Jesse Williams Sep 12 '16 at 18:07
• @hoffmale: I once dated a girl like that, and I agree you wouldn't want it. – A. I. Breveleri Sep 12 '16 at 20:45
• @A.I.Breveleri Half-frozen brains can also make dating very awkward. ;-) – Karl Sep 12 '16 at 23:22

• In cryo-sleep, maybe the body is not completely frozen (just slowed down on bio functions by a XXX-fold factor) and can repair itself at a slower rate. Given the centuries/decades of sleep in some starship travels (see the first Alien movie), clothing would rot away.

• The advanced society that has cryo-sleep (assuming society has evolved in all aspects, not just tech) has less need for modesty and are more comfortable with naked bodies (think star trek-ish).

• They are naked in cryo-sleep, but only the vitals monitor are visible anyway, so no peeking. As an inconsequential part of the awakening process you can include ubiquous nanite / 3D printing of new clothes anyway, so why bother storing people clothed.

• why would clothing rot at temperatures so low that basically everything able of having a metabolism is frozen? – hoffmale Sep 12 '16 at 13:48
• +1 for being the first answer I came to point out the basic problem with the question - unnecessary hangups. Plenty of people and current societies have no particular issue with being nude. Every person who has ever existed has a body - get over it! – GrinningX Sep 13 '16 at 13:44
• @hoffmale stated in the answer already: while the almost-frozen body can slowly repair itself, the clothes can't. – Mindwin Sep 13 '16 at 13:50
• @Mindwin: how would it rot? When clothing normally rots, there are microorganisms involved, who destruct the material until it isn't usable anymore. However, at the low temperatures used in cryonics, it would be impossible for any microorganism to be active (if they were active, so would be other microorganisms that destruct the human). It's logically unsound (unless I'm overseeing a way in which it still could rot). – hoffmale Sep 13 '16 at 14:36
• @hoffmale you are disregarding the assumptions contained in the first bullet point. - maybe the body is not completely frozen - note that these assumptions are only valid for the first bullet point. The other ones are independent. – Mindwin Sep 13 '16 at 14:39

The main function of clothing is to hinder the flow of heat. The last thing you want to do when putting people into cryogenic sleep is to hinder the flow of heat. Quite the opposite: You want to have perfect control of the temperature on the skin.

So, you say, why not put on some special clothing that conducts heat well? Well, the insulation effect is not just coming from the clothes material itself, it also comes from the air it encloses. When you enter the cryogenic tank with your special tank clothes, it is almost certain that somewhere there will be a pocket of air that's caught in the clothes and not driven out by the cryogenic fluid. And that will insulate you.

OK, but what if you find a way to reliably get all air reliably moved out completely, so your suit is completely filled with cryogenic fluid? Well, the most efficient heat transport mechanism is convection, and that is what the cryogenic chambers will use as well. The clothes will prevent that convection to reach your skin, and therefore the cryogenic substance in between clothes and body itself will act as thermal insulation. Note that on normal use, also the air acts as insulation only because it is held by the clothes.

Well, OK, so let's make an elastic metal body suit that's actually "vacuumed" directly onto the body, with absolutely nothing in between the suit and the skin. That should finally work, right?

Well, probably. But I'd expect that experience to be so unpleasant that you'd really prefer being naked.

Chafing

Similar but unrelated to bed-sored. Cold skin is more prone to chafing. Cryo-sleep is generally used for extremely long periods and unless there is close to no vibrations the wear on the skin over a prolonged period of time could be traumatic as if the body is comletely shut down it will be unable to repair the damage.

This could be mittigated with specialist clothing, but the cheapest and simplest solution is no clothing.

• How is chaffing against your constraints etc. avoided? – AnoE Sep 15 '16 at 11:34
• The contstains are either designed to be low friction/low chafing at contact points, or the sleeper is suspended in a gel, which is more efficient at maintiaining the appropriate temperature than a gas medium. – Jon P Sep 16 '16 at 0:16

A lot of well thought out answers so far. However, Cryo-sleep is pretty much entirely speculative at this point, so I strongly suspect that appeal to the present day audience is a more relevant factor than many others - especially when talking about movies or television. Let's face it, we all should realize that gratuitous nudity sells seats in theaters and having a reasonable basis for it helps to assuage many who might otherwise be grievously offended.

Some points on which I find I have to comment:

• nudity to avoid abrasion against clothing; if in cryo-sleep of almost any kind, it would be necessary to immobilize the body (or whatever part of the body that is retained) - particularly if traveling in free fall - or friction burns are likely to be the least damaging of the problems that could be expected to occur over a long period of time (being repeatedly bashed against the inside of the cryogenic container comes to mind).
• vibration protection; as anyone knows who has moved furniture or other valuables strapped into a truck, protection - such as might be expected from padded and flexible materials (not everything freezes into rigidity at anything above 0 degrees Kelvin) - will actually help to protect against damage from vibration (especially against straps or other restraints).
• saving of energy; some speculative fiction actually supposes that only the head needs to be preserved as the rest of the body can be reconstructed (the head is retained mostly to preserve memory - which is essential for identity) hence (if energy savings was important) most of the passengers on a long space voyage would be in relatively small chambers - saving a great deal more energy than simply discarding clothing (crew members might be stored intact, assuming there would be some delay in re-constructing their bodies).
• an argument can easily be made that one can greatly reduce chafing as an issue by putting (whatever remains of the) bodies in tight fitting suits that can be magnetically manipulated as they could be kept in light-weight "magnetic bottles" largely eliminating many issues with chafing and bouncing around.
• in at least some speculative fiction, cryo-sleeping travelers are not only clothed, but clothed in a suit capable of providing some protection from the consequences of destruction of both the cryo-sleep container and the surrounding vessel.

It would save fuel. Under the assumptions: That clothes can be manufactured in space from debris. Freezing bodies uses different equipment to maintaining, and defrosting.

It would be worth only launching weight that you have to, so removing clothes for a large number of people would be a considerable save in fuel.

• In several SFnal futures limbs and even whole bodies can be regrown. In which case it's not necessarily just the clothes which can be recycled to save fuel. – nigel222 Sep 13 '16 at 9:54
• @nigel222 Ya think of the savings if you amputate the passengers' limbs. Maybe just "coach" class? Gives "leg room" a whole new meaning. – Dronz Sep 13 '16 at 20:01
• @Dronz Why take your body in the first place? Just put a brain in a jar, and reconstruct a body on the destination. Imagine how many people you could fit in a starship that way! :D – Luaan Sep 14 '16 at 12:31
• @Luaan Why not just upload your consciousness to a digital matrix for travel? Then you can reload your consciousness upon arrival into a waiting lab-grown body for continued human experiences – TylerH Sep 14 '16 at 16:20
• @Luaan Hehe. Of course, apart from ridiculousness and suffering and impracticality and the need for fantasy regeneration tech and so on, the "other" real reason is that the person isn't really limited to the brain. Memories and emotions and who we are is also encoded throughout the body - the arms and so on aren't just mechanical tools, but are major parts of the nervous system that are part of "us", too. – Dronz Sep 14 '16 at 22:01

I don't have any specific (or even non-specific) links I can cite here, but another reason for this (beside the technology-based answers here) is that it's a plot device for the benefit of the audience in eliciting an emotional response.

Awaking from cryogenic sleep can draw parallels with a re-birth. The audience would see (or read) of a gradual and somewhat traumatic wake up process, naked and covered in slime or fluid/membrane (i.e. amniotic fluid/sac). This provides more of a plot device than someone simply waking up.

Remembering that you asked this in the context of movies...

it's because it gives a scientifically/medically plausible excuse to show as skin as possible of the good looking people that are usually hired for the roles.

Beautiful bodies that are partially naked, or if the rating allows completely naked, sell movie tickets.

You would be wet when you awake, and it would be faster to warm you up when you get out the cryogenic bath, which is supposed not to be clean water. No need to take your clothes out at that moment, and no need to clean them or dry them off. Just like when you enter and get out of a swimming pool. I see it otherwise: why would you want to have your clothes on?

The style of clothing would rapidly become out of date making the person look ridiculous.

Unless, like the Freezer Geezer, one leaves instructions to specifically "alter my pants as fashion dictates"