Med School Insiders has a video on getting enough sleep while dealing with the very demanding schedule of someone early in their medical career. It's a field notorious for early starts and long hours, so what's successful for them is probably worth listening to for anyone needing a little more spring in their step.
Many peoples' solution to this problem is coffee, but that's actually something that doesn't come highly recommended from experts. Some say it's best to use it only when you really need it. It's also worth checking out these tips on how to combat constant tiredness.