I can't find it now, but I came across an image with some alternate sleep patterns. Some really weird ones to minimize sleep, like taking 30 minutes naps every so many hours instead. One that caught my eye made me realize that I have a "bi-phasic" sleep pattern. For most of my life I've always been able to get by with like 5-6 hours of sleep. Some work days I'll be a bit more tired so I'll just take a quick nap during lunch.