Phantom Bell at four in the morning?

It was 4:00 in the morning and i had just lied down i was just about to fall asleep when i heard two bike bells ring right at the bottom of my bead. It scared me at first but i put it off as my imagination i lied back down and a few minutes later i heard it again i got up and couldnt sleep for the rest of the night. The bell was loud and clear and sounded exactly like a bike bell even though no one in my home owns a bike. After hearing it I did some research and found some stories that were nearly identical they all happened at four in the morning and sounded like a bell the only difference was the type of bell. I have never experienced any paranormal phenomena in my household which is a modernly built house and none of my family members have died recently. BTW please dont call me crazy, its not like im hearing voices, this is the only thing i have experienced.