Intensive Care Medicine

, Volume 33, Issue 11, pp 1954–1958

Light and darkness fail to regulate melatonin release in critically ill humans


DOI: 10.1007/s00134-007-0769-x

Cite this article as:
Perras, B., Meier, M. & Dodt, C. Intensive Care Med (2007) 33: 1954. doi:10.1007/s00134-007-0769-x



Pineal dysfunction has been associated with morbidity and mortality in various animal models of severe illness, and low melatonin plasma concentrations have recently been reported in patients on the ICU. However, it is not known whether the physiological response of the pineal gland to light and darkness is preserved in critical illness.

Design and patients

We examined the nocturnal release of melatonin in response to 1 h of darkness followed by 1 h of bright light (> 10,000 lux) in 20 severely ill patients on a medical ICU. Eleven elderly (median age 73 years) and 9 young patients (38 years) were recruited. Melatonin plasma concentrations were measured at 30-min intervals.


In 15 patients melatonin plasma concentration was low and responded to neither darkness nor light. In three elderly and two young patients melatonin plasma concentrations were elevated irrespective of illumination.


The physiological regulation of melatonin secretion by darkness and light is abolished in severely ill patients.


MelatoninIntensive care unitCritical illnessBright lightDarkness

Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  1. 1.Department of Internal Medicine IUniversity of Schleswig-Holstein, Campus LübeckLübeckGermany