"Their bodies forsake their beds of sleep; they call on their Lord, in fear and hope, and they spend (in charity) out of the sustenance we have bestowed on them" (as-Sajdaah: 16)
One may wonder - why is it this verse is praising those who forsake sleep? It certainly isn't a sin to rest. In fact, it's a dispositional necessity for every human being to sleep. But let us examine our lives and think about our day to day actions and dealings. Every human being, deliberately or subconsciously, categorizes their daily deliverables in spheres of priorities. There is the sphere of 'urgent' tasks, then there's 'high importance'....., "not so important"... so on and so forth.
Picture a student, their studies will always be in either the sphere of "high importance", or at least "importance", depending on their commitment to their study. When examinations draw near, however, studies shift in to the "urgency" sphere, displacing everything else out. Sleep is no longer a concern for the pressurized student, they may endure long days on a very few hours of rest and very little food and drink as their mind is focused solely on the examinations ahead.
Similarly there are servants of ALLAH whose commitment and Love for ALLAH, and their desire for His reward, has occupied their uppermost priority sphere, consistently, to the extent were sleeping isn't of major importance. They will stay the nights up praying and remembering. The surplus of their wealth will go to feed the hungry and the needy. Those who've reached this level find their food and drink in mentioning ALLAH's name on their tongue. Their rest becomes the moments they spend in sujood while others are cuddled in their blankets. Their utmost comfort and satisfaction is in standing before their Lord in prayer. They acquire the true sweetness of faith. They buy with their possessions and comfort the eternal prosperity of ALLAH's heavens. We ask ALLAH to make us all among them...