How Sleep Affects The Brain...

Sleep helps solidify memory.
It helps consolidate long-term memory by strengthening certain neural connections and getting rid of unwanted ones. You've probably noticed how sleep has helped you remember something you've learned during the day.

Toxins are cleared during sleep.
In recent years, it's been discovered that the brain clears out toxins much more quickly while we sleep rather than when we're awake.

Sleep is necessary for cognition.
Sleep deprivation can impact cognition, decision-making, ability to multi-task, as well as attentiveness.

Creativity needs sleep.
When you're sleep-deprived, your ability to think outside the box in new and imaginative ways is severely affected.

Sleep loss and depression are intertwined.
Those with depression often have a hard time sleeping (causing their symptoms to worsen) or they may sleep a lot. The part of the brain that manages circadian rhythm (daily sleep-wake cycle and all the bodily functions that depend on it) is disrupted in depressed people- which may help explain why depression and sleep problems are intertwined.

Physical health and longevity.
There are numerous studies linking lack of sleep to mortality. The effects of sleep deprivation most likely have to do with its effects on our hormones, but that can increase the risk for diabetes and inflammation too.

Kids need sleep.
Sleep deprivation in kids has numerous short-term ramifications, but it can also affect brain development in the long run.

Source: http://www.forbes.com/sites/alicegwalton/2016/12/09/7-ways-sleep-affects-the-brain-and-what-happens-if-it-doesnt-get-enough/