Question about bbt

Sandy • married to the love of my life, suffered a MC 8/27/14 but we are trying again. My 2nd his 1st
My husband and I are both 40 been trying to conceive unsuccessfully since our miscarriage in Aug 2014. I want to start tracking bbt but I'm concerned about how accurate it will be. I sleep off and on all night, rarely leaving the bed unless I have to pee. Will it be accurate even though my sleep patterns are all over the place??