It's really not possible to "hack" your sleep schedule effectively for any length of time. True, some people, called "short sleepers" do function rather well on 3-4 hours of sleep a night. But, most people require an average of 7-9 hours of sleep, and when they deviate from that for any length of time, they eventually rebound to their required length of sleep.
When you do try to "hack" your natural sleep schedule, you end up tired, and functioning sub optimally. Scientific studies have shown that people who are chronically sleep deprived are as dangerous behind the wheel of a car as someone who is legally intoxicated. Why would you do that to yourself willingly?
There is a lot of good scientific research being done in the field of sleep medicine. There are physicians who specialize in sleep. I've been going to one for the past year. And, while sleep medicine is a young discipline, a sleep doctor can be quite helpful.
If you're tired all the time, may I suggest you see a physician who has studies and specialized in such things instead of trying to diagnose and treat yourself via the internet.