All studies involving men measured T or TT levels in relation to age, whereas some also analyzed DHEAS [11,15], IGF-1 [13,15], BMI [10], type of work [12,14,15,16,17,18], andropause symptoms (with the AMS scale [12,14]), job content (with the JCQ questionnaire [12,14]), lifetime SEP [13], and sleep disorders [16,17]. Here, IGF1 is linked to sleep disorder.