13 people participated in two nights of sleep. I didn't see anything about a control group, or any control for the day preceding the night of sleep. I tend to

13 people participated in two nights of sleep. I didn't see anything about a control group, or any control for the day preceding the night of sleep. I tend to agree with this study, because of my personal experience with sound and its affect on my sleep, but I don't think this is anything but a reason to do a more in-depth study.