Researchers have peered into the brains of the baby zebrafish — through their transparent skin — and found that their brains have fewer synapses when they sleep. This probably holds true for humans too.
Synapses are the neuron-to-neuron connections inside the brain, and while we rest, the number of connections drop, which is thought to let the brain recharge and function better when awake.
Researchers say this cycle is likely governed by our own circadian clock, sleep, and the newly identified gene, NPTX2b, which exerts some control via an unknown mechanism.
Once this discovery becomes better understood, I'm betting we'll see a mammoth surge in polyphasic sleep plans, designed to tweak your sleep schedule to maximize your synapses for when you really need them.
Research published in Neuron