Sleep, references to the buddha and other arhats I have heard on various occasions that the Buddha slept very little. I was wondering if there is any theory out there that explains this. I was also looking for some specific reference in the literature that can attest to this.

My question doesn't refer specifically to the buddha, it could refer to any trained person.

Thanks.
I have heard on various occasions that the Buddha slept very little. I was also looking for some specific reference in the literature that can attest to this.

One of the most common references in the early texts is the wakefulness (jāgariya) pericope:


  "And how is the disciple of the noble ones devoted to wakefulness?
  There is the case where a disciple of the noble ones, sitting &amp; pacing
  back &amp; forth, cleanses his mind of any qualities that would hold the
  mind in check. During the first watch of the night [dusk to 10 p.m.],
  sitting &amp; pacing back &amp; forth, he cleanses his mind of any qualities
  that would hold the mind in check. During the second watch of the
  night [10 p.m. to 2 a.m.], reclining on his right side, he takes up
  the lion's posture, one foot placed on top of the other, mindful,
  alert, with his mind set on getting up. During the last watch of the night [2 a.m.
  to dawn], sitting &amp; pacing back &amp; forth, he cleanses his mind of any
  qualities that would hold the mind in check. This is how the monk is
  devoted to wakefulness."
  -MN 53, Trainee Practice


Notice that, in the second watch, sleep (niddā) is not mentioned. It mentions only lying down on the right side in the lion's posture (dakkhiṇena passena sīhaseyyaṃ kappeti). This could be an indication of not sleeping at all and continuing to practice mindfulness while, at the same time, resting the body.
On the other hand, the absence of the line "he cleanses his mind of any qualities that would hold the mind in check", which is included in the first and last watch, may indicate a less active practice or even sleeping.

I'm sure there are more references regarding this theme but I don't recall any additional ones at the moment.