It's undeniable that we need proper sleep not only to maintain our physical and mental health but also to function in our everyday lives. We consider eight uninterrupted hours of rest the marker of a healthy lifestyle - but is that really all that constitutes 'proper sleep?'
Some scientists have argued that we may not be built to sleep through the night in one long stretch. Our ancestors experienced sleep in a very different way. In the 18th century, people may have slept in two separate nightly intervals, rather than one eight-hour period.