If it takes you quite a while to fall asleep at night, then you're in good company. Many people struggle to slip into the Land of Nod for a wide variety of reasons. It's normal to take 10 to 20 minutes to fall asleep once you climb into bed (this is called sleep latency). If it takes more or less time than that, then your body may be trying to tell you something.
If it takes you an hour or longer to nod off: You may be sleeping too much or you may be grappling with insomnia. This can happen if you have trouble relaxing and turning off your thoughts at night. It can also happen if your body isn't ready for sleep because you had too much caffeine or your internal clock is out of whack for another reason (such as jetlag). The first step is to try to improve your sleep hygiene. If that doesn't help, talk to your doctor about what you can do to fall asleep more easily.
If you fall asleep as soon as your head hits the pillow: This may be a sign that you're not sleeping enough. In that case, you're on notice that you should make it a priority to get more snooze time. If you don't, skimping on sleep is bound to catch up to you eventually—and probably not in a good way.