Table 1.

Summary of sex differences in orexin measures. Summary of the literature reporting sex differences in orexin measures in both preclinical and clinical studies. Details concerning the exact orexin measure and analysis method, whether it was increased in females compared to males, and citation for the study are included.

Orexin measure and method	Sex difference	Citation
Preclinical studies
Orexin A in the lateral and posterior portion of the hypothalamus measured by radioimmunoassay	Higher in female rats compared to male rats	Taheri et al. (1999)
Prepro-orexin, OX1R, and OX3R mRNA in hypothalamus measured by QPCR	Prepro-orexin and OX1R higher in female rats compared to male rats; OX2R no sexual dimorphism	Jöhren et al. (2002)
OrexinA/cFos dual stain in the lateral hypothalamus measured by immunohistochemistry and orexinAlevels in the cerebrospinal fluid measured by radioimmunoassay	Higher in female compared to male rats	Grafe et al. (2017)
OX2R gene in the paraventricular nucleus of the hypothalamus measured by transcriptomics	Higher in female compared to male rats	Loewen et al. (2017)
Clinical studies
Orexin A in the plasma measured by radioimmunoassay	No differences between healthy men and women	Arihara et al. (2001)
Orexin A in the cerebrospinal fluid measured by fluorescence immunoassay	Higher in women compared with men (with or without Alzheimer’s diagnosis)	Schmidt et al. (2013)
Orexin A in anterior cingulate cortex and dorsolateral prefrontal cortex measured by immunohistochemistry	Higher in women with MDD compared with men with MDD	Lu et al. (2017)