Postoperative elevated cortisol excretion is not associated with suppression of 6‐sulfatoxymelatonin excretion

Elevated postoperative cortisol is associated with lower nocturnal 6-sulfatoxymelatonin excretion in surgical patients.

• Postoperative patients show disturbances in circadian rhythms and suppressed nocturnal melatonin levels.
• Total and peak nocturnal 6-sulfatoxymelatonin excretions were significantly lower on the first postoperative night compared to the second.
• The timing of the nocturnal cortisol low point preceded the surge in 6-sulfatoxymelatonin for 20% of patients on the first night and 75% on the second night.
• A lack of consistent relationship between cortisol levels and 6-sulfatoxymelatonin suggests that cortisol may not directly cause the suppression of melatonin in postoperative patients.

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