Cows' Body Clocks Get Confused by Light Changes
Effect of circadian system disruption on the concentration and daily oscillations of cortisol, progesterone, melatonin, serotonin, growth hormone, and core body temperature in periparturient dairy cattle.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Scientists changed when lights were on and off for pregnant cows to see how it messed with their body rhythms. They found that when lights were shuffled, the cows' body temperature and some hormones didn't follow their usual daily patterns like they did with normal light schedules.
Surprising Findings
Cortisol rhythms were unaffected by light-shifting, despite being a stress hormone.
Most assume stress hormones like cortisol are highly sensitive to light disruption—yet here, cortisol levels and rhythms remained stable even when other hormones (serotonin, melatonin) were thrown off.
Practical Takeaways
Avoid frequent light schedule changes during late pregnancy (for humans or livestock) to support stable circadian rhythms.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Scientists changed when lights were on and off for pregnant cows to see how it messed with their body rhythms. They found that when lights were shuffled, the cows' body temperature and some hormones didn't follow their usual daily patterns like they did with normal light schedules.
Surprising Findings
Cortisol rhythms were unaffected by light-shifting, despite being a stress hormone.
Most assume stress hormones like cortisol are highly sensitive to light disruption—yet here, cortisol levels and rhythms remained stable even when other hormones (serotonin, melatonin) were thrown off.
Practical Takeaways
Avoid frequent light schedule changes during late pregnancy (for humans or livestock) to support stable circadian rhythms.
Publication
Journal
Journal of dairy science
Year
2022
Authors
A. Suárez-Trujillo, Nguyen Hoang, Leela Robinson, C. Mccabe, D. Conklin, R. C. Minor, J. Townsend, K. Plaut, Uduak Z. George, J. Boerman, T. Casey
Related Content
Claims (6)
Cortisol secretion follows a circadian rhythm entrained primarily by environmental light exposure, with secondary modulation by feeding timing and psychological stress.
Before giving birth, cows have daily rhythms in body temperature and key hormones, but after birth, these daily patterns disappear, no matter if their light schedule was changed or not.
As cows get closer to giving birth, their bodies start showing stronger daily patterns in stress hormones, pregnancy hormones, and mood-related chemicals — but only if they’re on a steady light schedule.
The daily changes in body temperature and hormones in pregnant cows aren’t controlled by just one clock — they’re shaped by at least two different timing systems working together.
When cows are kept on a changing schedule of light and dark before giving birth, their bodies produce less serotonin and more melatonin, which might affect how their internal clocks work.