"If we really intend to submit our body as a living sacrifice to God, our first step may be to start getting enough sleep. Sleep is a good indicator of how thoroughly we trust in God. The psalmist, who knew danger and uncertainty well, also spelt well: 'In peace I will both lie down and sleep, for You alone O Lord make me to dwell in safety' (Ps4:8)
...for if we are not rested, the body moves to the centre of our focus and makes its presence more strongly felt; the tendencies of its parts call out more strongly for gratification.... Rest, properly taken, gives clarity to the mind. Weariness, by contrast, can make us seek gratification and energy from food or drugs, from various illicit relationships, or from egoistic postures... they pull us away from relying on God, and from living in his power."
(Willard & Simpson 'Revolution of Character' p141-2)
Read this today, and it rings true for me. I must admit I'm far more likely to faff about online if I'm tired than if I'm fully rested and alert. Does that happen to anyone else or is it just me?