How many hours of sleep do you need in a night?

My body runs best on about five hours of sleep. I know the recommended dose of sleep is eight hours, but if I sleep that long I feel groggy and exhausted all day. Once a week I’ll sleep for about 12 hours in one night and that seems to recharge my battery. When I was a teenager I only slept about 3 hours a night and was fine. The doctor said that it wasn’t insomnia because insomniacs are constantly tired but can’t sleep. He just said I was lucky to not need as much sleep.

Do you have odd sleep patterns? Is eight hours too little or too much for you?