Ilikepie5 is correct... You are assuming all that ngs regularly burn energy to tend to their fragile biological body that's tiring and burning energy as it functions in a straightforward manner.
To begin to display why ilikepie5 is correct rhat we have no clue of the limits and possibilities, if you knew the typical things about land-based mammals and respiration, you'd never ever believe that dolphins, whales and seals (plus walruses, sea lions etc) function healthily and without severe brain damage and cramps.
If you only knew mammals, the idea of how fish reproduce would be absurd as not only are they using eggs outside of their body but the insemination actually is done by the male directly to the eggs, no actual sex is involved unless we look into some shark species or some extreme exceptions.
We are in a world interpreted through ojr five senses and forms of life evolved to fit this planet's means of providing for life firms within it, with microbial entities as the basis of life here.
If the aliens evolved from non-microbial life in a way that operates extremely different (maybe they can rip their gody apart and reattach it with ease meaning they can teleport parts of themselvea at a time) as well as having something very different to blood, glucose etc as their way of fuelling their operations, it follows that what we consider respiration to be may be very different for them.
Respiration is linked to dependency on constant energy, some alien species may have the capacity to essentially store massive battery charges of energy that then lets them not respirate for a while. Salmon actually do this, it's done especially hy Canadian salmon amdnis how they famously leap out of water in the way they do that lets bears catch them. During this trip they suffocate themselges by essentially being on ansuicide mission to travel superfast without cramps so they reach the destination and are in a safer environment to have offspring and then die.
It's probably true that respiration, as in the conversion of energy into a form that the lifeform can use, is there for alien lfieforms hut if this battery charge mechanism is in place (for instance) it already is much more feasible for them to be suffocating naked in outer space (if they're able to stand the conditions) and remain alive. If this is actually viable it starts to change how dangerous and effective they can be at dominating other planets, especially if they aren't perceptible to our five senses (though I think they'll always be perceptible to touch). There's also the idea that rhey are demigods of sorts. Demigod aliens may genuinely be personalities that aren't respirating, just operating on immortal consciousness.