Circadian rhythm presents itself primarily in sleep, eating habits, and other activities. These patterns will be disrupted when circadian rhythms change (Guo 2013). For example, in the hand-eye coordination exercise, students took longer at night and were faster during the day (Fig. 2). This is reinforced by studies (Boudreau 2013) that show people work less efficiently when circadian rhythms are disrupted. Furthermore, in the speed addition function (Fig. 4), students performed slower at night but progressively faster during the day. This is supported (Phillips 2013) in the case that everyone is remarkably diverse and flexible in their daily activity.