Is Sleep a neccessary Biological Function

[Zero]

I was wondering if it is considered a basic biological function say like breathing that all organisms must sleep. I was brainstorming some ideas for an alien species and thought wouldn't it be cool to have these aliens that never sleep. Would be kind of freaky. But then I wondered if that was biologically impossible for an organism not to have to sleep. Anyone have any thoughts on this?

You could always claim that this alien species has a similar physiology to ours, but has the ability to sleep one hemisphere of the brain at a time, and thus avoid the inactive 8-hour period we face every night.

[18-Till-I-Die]

Its possible, as their technology progressed, these aliens managed to implant something in their brain, some kind of 'bio-surgery' if you will (to steal a 40k term for genetically engineered biomechanical implants) and this allows them not to sleep.

In Space Marines, they require no real sleep. If they need to, they can enter a dreamless coma state for hibernation, requiring no food or water, and 'live' for centuries until they are awakened. Its a defense mechanism if i recall.

But they dont physically require sleep to live. One bunch of Marines, managed to go for 300+ hours without sleep and supposedly tehir combat functions were not lessened (from the impression i get, they were in direct combat the entire time, i guess like trench warfare or street to street fighting something that made sleep impossible for risky).

Space Marines do sleep from time to time. But from what i've read its mainly just because they still psychologically feel the need, having once been human. They no longer medically, physically require it but there is still a psychological 'addiction'. So they lay down and close their eyes feigning sleep, in this dreamless fogue.