How to prevent falling asleep during meditation

If you are falling asleep during meditation, then there are several things you can do to prevent it.  Below are a list of ideas to try that should help you meditate properly:

1. What type of position are you doing? Chances are you are in a position that lends itself to falling asleep. For instance, the corpse pose (lying on your back) is a perfect example. Try meditating in a sitting position like the burmese or half-lotus pose. If you must lie on your back, then modify it to reduce your chances of falling asleep. For instance, you can bend your legs at the knees.
2. What time of day are you meditating? If you are meditating late at night, try meditating earlier when you have more energy.
3. Have you eaten before meditation? If you have eaten a big meal before meditating then it is a good idea to wait a couple of hours before beginning a meditation session. After eating your body goes into parasympathetic mode. This means most of your energy is being put into digesting your food and it is wise to let your body focus on this task.
4. Are you tired? Are you tired before you begin the meditation session. Make sure you feel well rested before you begin a meditation session. This is also related to point 2 above. If you can only meditate at night, then try a guided sleep meditation. This will improve the quality of your sleep and help you feel more well rested. 
5. What is the temperature in the room? A hot room lends itself to a person falling asleep.
6. Are you getting enough sleep at night? Sleep is important to the health of your body (mental/emotional and physical). Make sure you are getting enough sleep at night. This along with meditation will benefit you tremendously. As stated in point 4, you may want to try a guided sleep meditation to help improve the quality of your sleep.