The first of these is the weather. Although it was a sunny day, large clouds continuously blocked the sunlight, making it impossible to see the shadow. If this occurred around the time that the hourglass indicated an hour had passed, I had to wait a few minutes for the clouds to move so that I could see the shadow. Thus, some hours on the sundial may appear to be longer or shorter than others. Another major weatherly hindrance that I have thus far observed is the rain.
Participants were asked to go about their days as they would normally, except without watching television or playing video games. Participants were also asked to keep a sleep diary in order to record possible explanations for sleep abnormalities. One experimental day consisted of playing a computer game for an hour. Another experimental day consisted of watching a movie of the participants’ choice between the hours of 6 and 7 in the evening. The other experimental day consisted of the sleep