Abstract
Background: Menstrual cycle is due to cyclic variations in the levels of various sex hormones. The effects of these hormones are not limited to the reproductive system alone but affect other systems including the nervous system.

Aims and Objective: To study the reaction times (visual reaction times [VRT]/auditory reaction times [ART]) during the three phases of the menstrual cycle, i.e., menstrual (M), proliferative (P), and secretory (S).

Materials and Methods: This cross-sectional study was conducted on 50 healthy young unmarried females in the age group of 20-25 years, having regular menstrual cycles. VRT/ART was measured during the menstrual, proliferative, and secretory phases. The results of the reaction times were subjected to statistical analysis using Student’s paired t-test for comparison of means. P < 0.05 was considered as significant.

Results: The average reaction times (in milliseconds) during the different phases of the menstrual cycle were as follows: ART = M - 187.23 ± 19.20, P - 182.58 ± 14.63, S - 178.23 ± 13.14 and VRT = M - 190.37 ± 8.83, P - 185.79 ± 10.70, S - 181.53 ± 15.11.

Conclusion: Both the ART and VRT’s were longer during the menstrual phase, whereas they were shorter during the secretory phase of the menstrual cycle. The prolonged reaction times during the menstrual phase is attributable to the slowing of conduction times, due to fluid and electrolyte increase. The quicker reaction times during the secretory phase is probably due to progesterone negating the ability of estrogen to cause conduction delay.

Key words: Reaction Time; Menstrual; Proliferative; Secretory; Sex Hormones