Approximately 90% of women in the United States report physical or emotional changes prior to and during their period. These changes can include symptoms such as fatigue, cramps, reduced concentration and memory, sensitivity to noise and light, sadness, anxiety, irritability, mood swings, and sleeping too much or not enough. In the Fall Quarter of 2020, we collected sleep, mood, and menstruation data from 19 female university students over the course of 2 months. Participants wore Actiwatches to track sleep, light exposure, and activity. In addition, participants answered daily and one-time surveys about sleep, mood, and menstruation. We hypothesized that mood scores on menstruating days would be lower than scores on non-menstruating days. We analyzed differences in mean mood scores on menstruating days versus non-menstruating days. This mood score was on a scale from one to seven, with one indicating poor mood and seven indicating excellent mood. Since subjects reported significantly lower mood scores on menstruating days than on non-menstruating days, we aim to expand on research to uncover which variables impacted mood specifically. The t-test compared average scores for menstruating and non-menstruating per participant to allow us to compare results within and across all subjects. To test for other variables that may have contributed to lower mood, we will also examine how mood scores varied with participant birth control usage, activity, and natural light exposure. We hypothesize that additional variables such as natural light exposure and activity may have contributed to the statistically significant difference between mood reported on menstruating vs. non-menstruating days. Our work is important because while menstruation is extremely common, research on variables that impact mood during menstruation is often inconclusive or minimized by stigma.