Smiling at the little wailing thing that is the cause of one’s lack of sleep / headache in order to let him have a pleasant awakening. Though the initial few seconds may be forced in order to get over the sleep-deprivation induced grumpiness, the smiling, somehow, quickly becomes genuine.
The kid decided that he was hungry and wanted to play at 04:00. Thankfully he was amenable to playing by himself in the dark in his crib and slowly falling back to sleep.