When keeping a Basal Body Temperature Chart remember that by waking at the same time everyday, the chart is more accurate. However, if the waking time varies, the tempertures tend to creep up about two-tenths of a degree for every extra hour you sleep.

It is important to remember that you should have at least 3 hours of consecutive sleep, before taking your temperature.

Fever, a restless night's sleep, or alchohol consumption the night before can all make your waking temperatures higher.