Yes, that’s right, we have tested the optimum sleeping comfort position for 23 male subjects with “a buttock-to-knee length of 64.5–61.5 cm[…]representing the 30th to 65th percentiles of male Germans”. It was “for the sake of homogeneity” so that’s ok I guess, given the human race is famously super homogenous.
The paper does actually right at the end acknowledge that this may be a teensy problem, given
females sit with more anterior rotation of the pelvis as well as less flexion of the lumbar spine and thus, yield different contact pressure patterns (Dunk and Callaghan, 2005) [and] it has also been implied that women are more sensitive for contact pressures and have a lower threshold for the onset of discomfort (Binderup et al., 2010; Vink and Lips, 2017).
“Nevertheless,” they actually, genuinely say, with a straight face (presumably since I can’t actually see their faces), “the current study is the first of attempts in evaluating the biomechanical quality of in-vehicle sleeping positions based on interface pressure distributions.”
Well you can’t argue with that. I guess safety for women can wait.