Seven to nine hours is the recommended sleep time for the average adult. But why is it that people get less than six hours of sleep and seem to end up perfectly fine? What really happens when you only get 4 hours of sleep? 

Some say that it’s your sleep quality, not how much you sleep, that matters. So a short sleep cycle can be fine as long as you get good quality sleep. Others would suggest you absolutely need to get a full night's rest to be able to get restorative sleep – implying fewer hours is simply poor sleep hygiene.

In this article, we delve into whether 4 hours of sleep is enough, the 7-hour sleep standard, and the reasons why some people are able to survive with less sleep than others. We're also diving into ways to stay alert after a bout of sleep deprivation.