BBT experiences

Does your bbt go up after a restless night of sleep? Wednesday was cd16 and I had faint cramping at one point during the day. My 2yo was sick that night and was crying/whining off and on all night. I obviously didn't sleep normally but never got out of bed. My temp spiked the next morning (Thursday) and I was convinced I had ovulated on Wednesday. However, bbt was back down this morning. I have been ranging between 96.9 to 96.6 and yesterday it jumped to 97.4 and this morning it was 96.9 again. I was under the impression that your bbt stays elevated til your period. Is it accurate for EVERYONE or is it just something that isn't for me? Maybe I haven't ovulated yet? Just curious on opinions and other's experiences...