How do I slow down metabolism?

I know how to speed it up, I just eat activia yogurt, but now I think I sped it up too much cuz I am hungry every 2 hours and I eat sooo much protein and meats and breads (whole grain and wheat) for my meal and I am still hungry. I remember my metabolism began to slow down when I slept for an hour during the day. So should I just sleep for an hour again and it will slow down?