With our crazy modern lives, many of us sleep far less than the recommended 6 to 8. But scientists are now realizing that it's wreaking havoc on our brains, which drain out toxic waste when we're asleep.

Not enough sleep means some of that waste stays in our brains - and that's now believed to be connected to diseases like Alzheimer's.

Matthew Walker, professor of neuroscience and psychology at UC Berkeley, explained the findings of his latest research.