A new study looking at stress in medical students found that, counterintuitively, the “stress hormone” known as cortisol appears higher during the laid-back summer months.
Researchers at Poznan University of Medical Sciences in Poland looked at levels of cortisol — a hormone that is released into the bloodstream in response to stress and helps regulate blood sugar and salt — at different times of the year.
They took saliva samples from medical students on two nonconsecutive days during the summer and did the same for two nonconsecutive winter days. Samples were collected for a full 24-hour period to analyze daily fluctuations in cortisol levels, which are typically higher in the morning. The study subjects tended to have higher cortisol levels in the summer.
Dominika Kanikowska, lead author of the study, says more research is needed, but the results are surprising.
“We of course know seasonality in animals,” she says. “But more and more results show that seasonality is also connected with human beings.”
