Scientific evidence matches your anecdotes. There is a very small percentage of people whose genes allow them to only need 4-5 hours of sleep each night. It's s

Scientific evidence matches your anecdotes. There is a very small percentage of people whose genes allow them to only need 4-5 hours of sleep each night. It's somewhere in the low single digit percentages. For the rest of us, 7-9 hours are required for proper functioning. If we get by on less, we're functioning suboptimally whether we realize it or not.