Bbt question

Andrea
I don't sleep well at night and often wake every 1-2 hours. I take my temp each time I wake and log the temp after the longest sleep that night (it's usually the first sleep and I wake between 2.30-3.30) 
​My question is; is bbt reliant on your body being at rest for an amount of time (at least three hours I have heard)  or is it just to be taken at the same time to get a reading every 24hrs? Can not getting 3+hours sleep before taking temp disrupt my chart? 
​Many thanks ladies :)