Why did Ash sleep?

Probably dreaming of electric sheep all the way...

Probably dreaming of electric sheep all the way...

Like the refrence to hal from 2001/2010...

Someone just said 'ashes to ashes' and that lulled him off.

Nobody knew that Ash was an Android, he was undercover on the ship, so he pretended to be human by sleeping, eating and drinking etc. In Prometheus everybody knows that David is an Android, so he can just be himself.

in the two year journey to LM-223 David is awake and doing the maintenance of the others in hyper-sleep..so hes got a job to do..

I think Ash was in disguise to pretend to be human. Bishop and David however, were known that they are synthetics. Also, the synthetics require food. They don't have unlimited power and need to recharge through resting and food. Remember that Ash and Bishop both needed to be in the hypersleep and ate food like a human. That's why they are rather cyborgs than robots / androids because they are machines made to resemble real human as much as possible, just like the replicants in Blade Runner.

I prefer the term 'Artificial Person' myself.

You have my sympathy

It was pretty clear in Aliens that Androids dont need food .... and i think david too ...i think Fassbender or Ridley talked about an episode with holloway sayng David that he dont need an helmet to breath or something like that .

He was pretending to be a human. If Bishop sleeps thats an error on Cameron's part. And I'm pretty sure Bishop doesn't eat.

he could be pretending, maybe he was awake for years and then went into hypersleep like 12 hours before they all woke up

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just another pothole along the alien highway.

LOL @ melkor & ZetaR Androids are really there to bake cornbread before everyone else wakes up! What is the deal with cornbread in all these movies anyway?

@CBT1979; Synthetics do not need food, they can eat for social reasons but they gain no nutrition from the food they ingest. They do need to recharge once a year for approx 72 hours though. They are not cyborgs, a cyborg is a being with both biological and artificial (e.g. electronic, mechanical or robotic) parts, there is no organic structure within the androids we see in Alien or in the Blade Runner replicants. **Why people always bring the Blade Runner Replicants into the Alien universe is a total mystery to me... The answer is simple, Ash was a was hiding as human, sent by the company. If he didn't sleep the crew would have known he was an android. Here is a very good link explaining everything about the Alien universe Androids/synthetics: Click here-->[url=http://avp.wikia.com/wiki/Synthetic]Android types and Physiology[/url]