Motion sickness susceptibility fluctuates through the menstrual cycle

Area of Science:

• Neuroscience
• Human Physiology
• Women's Health

Background:

• Women exhibit a higher susceptibility to motion sickness than men, reporting more frequent nausea and vomiting.
• The underlying causes for this gender disparity in motion sickness are not fully understood, with theories involving the female endocrine system yielding contradictory findings.

Purpose of the Study:

• To investigate whether women's susceptibility to motion sickness fluctuates across different phases of their menstrual cycle.

Main Methods:

• Twelve healthy women, not on contraceptive medication, were subjected to Coriolis motion (whole-body rotation with head tilts) until moderate nausea was induced.
• Testing occurred on four distinct days: menstruation (day 5), ovulatory (day 12), mid-luteal (day 19), and pre-menstrual (day 26), in a counter-balanced order.
• The number of head movements required to reach moderate nausea was recorded as the primary measure of motion sickness susceptibility.

Main Results:

• The number of head movements to induce moderate nausea showed a trend across the menstrual cycle: 13.7 (menstruation), 14.3 (ovulatory), 15.4 (mid-luteal), and 16.9 (pre-menstrual).
• A statistically significant difference was observed between the susceptibility during menstruation (day 5) and the pre-menstrual phase (day 26) (p < 0.05).
• Susceptibility was highest during menstruation and decreased towards the pre-menstrual phase.

Conclusions:

• A significant trend exists for motion sickness susceptibility to vary across the menstrual cycle, being maximal during menstruation and minimal pre-menstrually.
• While this cyclical variation is statistically significant, its magnitude is insufficient to account for the entire difference in motion sickness susceptibility between men and women.