It says it right here: "Synaptic pruning and other mechanisms for synaptic plasticity allow for learning and memory, but they are energetically costly. Indeed,

It says it right here: "Synaptic pruning and other mechanisms for synaptic plasticity allow for learning and memory, but they are energetically costly. Indeed, one hypothesis holds that sleep is the price we have to pay for plasticity the previous day. (see here)" "Synaptic pruning and other mechanisms for synaptic plasticity" -- Being a generalist. "...they are energetically costly. Indeed, one hypothesis holds that sleep is the price we have to pay for plasticity the previous day." -- Requires more sleep. Here's the wikipedia article on Neuroplasticity: http://en.wikipedia.org/wiki/Neuroplasticity http://en.wikipedia.org/wiki/Neuroplasticity It is the process of changing your brain. When neurons fire together they wire together, forming a neural pathway. When they fire apart, they wire apart. So if you're doing one thing - programming requiring high amounts of logic, for instance - a certain bunch of neurons fire together. They start forming a pathway. If you then go do something else in the same day, requiring a different bunch of neurons to fire, say play an instrument or write a fiction story, you'll start forming a different neural pathway. If some of the neurons overlap, but not all, you might end up beginning to break down the pathway you were building earlier in the day. All of these activities require more energy than simply continuing to use the same series of pathways you built earlier in the day.