You’ve probably heard advice to get a good night’s sleep after studying for a test so that your brain retains the information better, and now there’s science to back that up. While you sleep, your brain uses that time of slower brain activity to shrink synapses by about 20%. These connections between neurons in your brain are what you use to learn new things. This shrinking process keeps your synapsis from overloading, so information is retained better. That’s why restorative sleep – at least 7 hours a night in adults – is so vital.