Future research should incorporate direct measurement of: (1) circadian phase via dim light melatonin onset or core body temperature rhythms; (2) hypothalamic–pituitary–adrenal axis function via serial cortisol measurements; (3) sleep architecture via polysomnography or multi-night actigraphy; (4) anxiety symptoms via validated rating scales; and (5) inflammatory markers (C-reactive protein, interleukin-6) given the bidirectional relationships between sleep, inflammation, and physical activity. Here, IL6 is linked to Anxiety.