Every time I get in bed I die

Every time I get into bed at night, i die. Even on peaceful mode. I tap the bed and.."Oof, oof, oof," I keep losing hearts, unable to move. What's going on? Is this a bug? Or am I doing something wrong?

P.S: I'm not sure what version I'm playing, I'm pretty sure it's 0.7.6, but I may not be correct.