Why do I fart all the time when I'm trying to sleep?!

I've been farting a lot for my entire life, but especially while sleeping. I usually sleep on my side, curled up, but sometimes on my back. I don't have any allergies or similar things that could be causing this as far as I know.

For example, last night was like this:

• I lay down, I fart twice
• I adjust my position, I fart again
• I roll on my left side, I fart
• I get up to fix my bed, I fart
• I lay down again, I fart

This is rather unfortunate because I like sleep with my head under the blanket.

Edit: as for my eating habits, my diet has consisted mainly of granola with 2-4 per day and miscellanous fruit and vegetables for the last 4+ years.