The effects of the chemical relaxer lye on hair cortisol concentrations

The analysis of hair cortisol is a common tool in stress research. External factors such as chemical hair treatments can impact the integrity of hair cortisol. The use of chemical relaxers is more common among racialized populations who experience high chronic stress and are underrepresented in stress research.

15 participants who identify as Black or Latinx were recruited to give a hair sample. The commonly used hair relaxer, lye, was applied to hair samples using a novel in vitro methodology to examine its impact on cortisol concentration.

Bayesian multilevel model estimated a small group effect (M = 0.53, 95 % CI [-8.57, 9.32]), with only 55 % of the posterior distribution favoring higher cortisol in untreated samples, indicating no meaningful difference.

The lack of effect of lye hair relaxer on cortisol supports the inclusion of participants who use this treatment in research and reinforces the utility of hair-based stress research in populations disproportionately affected by chronic stress. Addressing representation in stress research is essential, and these findings are a critical step toward developing more inclusive and equitable methodological practices.