The key to feeling refreshed is keeping them extremely short (think about 15 minutes tops), you need to wake up before hitting deep sleep or you have to wait for your next REM cycle to be over. It's admittedly pretty problematic when you have trouble falling asleep. My wife has this problem too, and she's a light sleeper on top, so naps don't work well for her. If I lay down for sleep, it happens in a matter of minutes, so a 15-20 minute power nap is easy and very efficient.
Everything they said, with the addition that falling asleep fast is a skill that takes practice to get good at. Even if you don’t fall asleep, laying down for 15 minutes can still be good for you. It allows your body to relax.
As for your mind, I’ve found that letting it wander and not trying to control it helps me get to sleep faster. Even if I’m thinking about things that stress me, if I let my mind go on its own, eventually it’ll go off the path and start thinking dreamy things. Next thing I know, I’m waking up.
No matter what works for others, it still takes practice.