Katy Perry refuses to overdo it when she's partying - because she's worried it will ruin her pop career.
The I Kissed A Girl singer calmed down her social life after seeing other stars ruin their reputation with a hedonistic lifestyle.
But she is adamant she won't quit having fun altogether - she just makes sure she always has an early night.
Perry says, "My motto has always been: live life to the full because at the end you're dead. But I'm starting to mellow a bit. I still believe in taking risks in my music, but I've realised that I can't party like I used to and expect to remain focused on my work.
"I've seen too many people live that way and almost wreck their careers. That's not going to happen to me. I'm still full on, but these days I see the wisdom in having a good night's sleep."