124 citations
,
  April 1992   in “Journal of Endocrinology/Journal of endocrinology”    Beard hair follicles have more androgen receptors than non-balding scalp hair follicles.  
      38 citations
,
  August 2012   in “Biochemical and biophysical research communications”
           38 citations
,
  August 2012   in “Biochemical and biophysical research communications”    Human leukocytes and beard hair follicle cells have internal daily clocks, and PER1 and PER3 genes may indicate individual circadian rhythms.  
               31 citations
,
  October 1971   in “Steroids”    Human beard hair follicles change testosterone into other related hormones, but don't much change androstenedione into testosterone.  
      12 citations
,
  January 2019   in “Sleep medicine”
           12 citations
,
  January 2019   in “Sleep medicine”    Night shift work disrupts the body's natural clock genes.  
               25 citations
,
  July 1994   in “Journal of dermatological science”    Testosterone affects hair follicles differently across body sites, with beard hair follicles showing more activity of a specific enzyme and presence of androgen receptors compared to scalp hair.