7 week old sleeping alot

Tonya
So my 7 week old baby girl put herself on a sleep schedule and the last couple days she has slept all day. And each day she sleeps longer and longer. Has anyone elses little one done this? Im a little worried. Im a first time mom she is exclusively breast fed and does not take a pasi, she has however been chewing on her fist and occasionally sucking her thumb when not hungry.