Insufficient sleep in the modern society causes dramatic health consequences and financial burdens for society. The biological mechanisms underlying the beneficial effects of sleep on cognitive performance are largely unknown, and it is this lack of insight that causes society to often neglect the importance of sleep. The group of A. Lüthi found that in a brain area essential for learning and memory, insufficient sleep disrupts the flexibility of cellular communication by altering information transfer through neurotransmitters. Their studies also reveal that synaptic plasticity of ex vivo brain slices strongly depends on the animal's recent history of arousal. This is an important novel concept in the field of physiology, indicating that the recent history of sleep and wake materializes in cellular brain function. By clarifying the cellular mechanisms underlying cognitive impairment caused by sleep loss, these findings will help to illustrate to the society the important role of sleep in brain function. Moreover, they could help in the development of new drugs to alleviate the consequences of insufficient sleep and to restore performance in professional or health circumstances in which sleep deprivation cannot be avoided - (see A. Luthi).