Anastacia's sister is her "creature comfort".
The 47-year-old star is currently in the UK rehearsing for her upcoming tour and revealed the only thing she needs to bring away with when she's away from home is her best friend and sibling, Shawn Newkirk.
Speaking exclusively to BANG Showbiz, she said: "My creature comfort is my sister. We're working together in the world of 'Anastacia' and there has to be four eyes watching it because my eyes are half the time crossed, I don't even know what's happening! But thank God she is the other brain that can make sure everything is really working.
She added: "It's true, there really doesn't need to be much more creature comfort."
Shawn was forced to leave the 'I'm Outta Love' singer for three weeks recently and the star admits it left her feeling out of sorts.
She said: "I was just without my sister for about three weeks because she was doing something else and I was just like, 'Oh my God, get here!' Just didn't feel like the same, it's not the same, my brain works better with her around. She's not getting freelance work, I will not have that. I will have to raise her salary! No, we're in it to win it, we're gonna grow old and die together."
Anastacia is set to take her Ultimate Collection Tour in support of her new album across Europe next month and fans will be able to choose the songs she sings via her new app SecondScreen.