Why am I falling asleep when I meditate?

I always considered meditation as a means of relaxing your mind and body. By my expectations, you’re doing great.

I recently did a guided meditation that gave me a new view of this. When the distracting thoughts come, don’t fight them, just observe them and move on. If you’re falling asleep you’re doing something right. :-)

Perhaps wear pajamas when meditating, just in case.

Very common.

The best policy is not to fight anything that comes up in your meditation. If you go into it with the idea that thinking is bad or drowsiness is bad, then when you get sleepy, or thoughts come up, you feel like you have to struggle to get away from the thoughts or to perk up. That really doesn’t work very well. When I fight the drowsiness, it usually just makes me fell even sleepier, and the same goes for the thinking.

Try this: Let go of the idea that the thoughts or the sleepiness are a problem that needs fixing. Treat them like the weather: as conditions that come and go, and that you really can’t do much about. Whether you like those particular conditions or not is beside the point; there they are. Be like a weather man: Your job isn’t to change the weather, it’s to pay attention to how things are. If you’re sleepy, bring your attention to the sleepiness without trying to push back against it. If you’re distracted, notice the distractedness and just keep gently bringing your attention back to your breath (or whatever focal point you’re using).

When you stop treating things like this as problems, they stop behaving like problems. I often find that my periods of meditation go through some very drowsy patches, and I’ve been doing this for a very long time. Same with distractions. It just doesn’t matter. All you need to do is keep nudging your attention toward its point of focus no matter what comes up.

You’re probably not getting enough sleep at night and you’re tired.

I’m with @Rarebear that you are probably sleep deprived. Relaxing through meditation helps you stop and allow yourself to rest.

Roll your hips forward. This forces your spine to straighten, allowing your organs to hang in their natural positions. You will notice an immediate improvement in breathing and alertness. You can stay awake and alert as long as you don’t forget and slip back into a slouch. When this becomes a habit then you will consider the slouch to be very uncomfortable.

This is a common problem. I used to go to yoga and people just snored around me because of the guided meditation thing. If you always fall asleep when calming down your thoughts, you can try focusing on the sounds you hear around you. Instead of using meditation to fall asleep, you can use apps like Sleep Automatic that play white noise which encourages you to sleep. If you use meditation to fall asleep for a long time now, your body recognizes meditation as a pre-sleep ritual and it associates it with sleeping. This might be your problem.