How can I go to sleep earlier??

I used to fall asleep around 10 or 11. Then, my cousin moved in with us & she had to sleep with me because the guest room was being used for about a month. The first night she stayed with me, it was good, I fell asleep early. The 2nd night, she was watching Netflix on her computer with the volume loud up until 3 in the morning. Im a light sleeper so I couldn't fall asleep & im also a very quiet, laid back person so I didn't comment on it. It continued until one night I gave her headphones & told her to shut up. One headphone didn't work so she took them off & again, it continued. Finally, the guest room was empty & she moved in but since then I haven't been able to fall asleep & im getting under eye bags & dark circles & it looks ugly.. how can I get rid of them & how can I fall asleep faster/earlier?