We recommend that you use the device over two consecutive nights. It is understandably easy to feel a little nervous going to bed with the device on the first night, and it is usually easier to get to sleep on the second night. It can be more of a challenge to get sufficient data with smaller children and we advise the two night option is selected here as well.. There is no extra charge for the second study, but we will provide only one report, using the study that provided the best data for analysis.