Sleep is necessary for the physical and mental wellbeing of any individual. The harmful effects of sleep deficiency are clearly demonstrated when humans or other animals are subjected to acute or chronic sleep deprivation, which results in deleterious effects on metabolism, cardiovascular function, mental health and cognition. In our recent study, we investigated the central mechanisms that are involved with the homeostatic and allostatic regulation of the wake-sleep cycle. We found two neuron populations that participate differentially in wake-sleep control; the median preoptic GABAergic neurons being critically involved in sleep homeostasis and the median preoptic glutamatergic neurons promoting sleep during allostatic (stressful) challenges.