There is a sutta I believe in the first book of the Samyutta Nikaya where a deva (or is it mara?) rebukes the Buddha for having overslept. This was apparently after the Buddha had spent all night in walking meditation. Hopefully someone knows the source. Ill have to do some digging around.
This is our foundation: to have sati, recollection, and sampajañña, self-awareness, whether standing, walking, sitting, or reclining. Whatever arises, just leave it be, don't cling to it. Be it like or dislike, happiness or suffering, doubt or certainty. Don't try to label everything, just know it. See that all the things that arise in the mind are simply sensations. They are transient. They arise, exist and cease. That's all there is to them, they have no self or being, they are neither ''us'' nor ''them.'' They are not worthy of clinging to, any of them. - Ajahn Chah