Yes. Just do your best to get as close as you can to the ideal. Fertility Friend is usually still able to make sense of your chart for you. If you have too much inaccurate BBT data, the analysis may be more difficult and less precise. If lost sleep is preventing you from getting an accurate chart and BBT reading and you are unable to remedy this situation, ask for help interpreting your chart. Also, pay close attention to your other fertility signs, particularly cervical fluid. This will help you to cross-check your BBT if it is ambiguous and help to ensure good timing your fertile window.