Editors' ChoiceCardiovascular Disease

How Can I Recover if You Won’t Let Me Sleep?

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Science Translational Medicine  09 Apr 2014:
Vol. 6, Issue 231, pp. 231ec65
DOI: 10.1126/scitranslmed.3009046

Disrupted sleep and shifted circadian patterns are bad for your health. So, what about the hospital intensive care unit (ICU)? The combination of critical illness, noise, staff interruptions, and abnormal light cycles in the ICU are potent disruptors of normal diurnal patterns. Cardiovascular health seems especially sensitive to disturbances to daily rhythms. The time of day strongly influences the incidence of cardiac arrhythmias and myocardial infarctions—and affects the size of the scar. Now, Alibhai et al. report that in mouse models, circadian disruption after an infarction impairs recovery and healing, findings that could prompt improvements in ICU care.

The investigators evaluated the effects of disrupted diurnal patterns by inducing myocardial infarctions in a group of 8-week-old C57B1/6 mice and exposing half to abnormal light-dark cycles while maintaining normal cycles in the other half. Even with only 5 days of diurnal disruption, an impressive array of adverse structural, functional, and metabolic changes were apparent. Mice exposed to altered light cycles showed notable abnormalities in long-term cardiac remodeling (larger hearts with worse function), hemodynamics (early evidence of heart failure), metabolic characteristics, inflammatory responses, and infarct-related blood vessel formation. Together, these findings paint a picture of strong and permanent adverse effects from a single, short interruption of normal diurnal patterns immediately after a myocardial infarction—disruptions similar to those commonly experienced by patients in hospitals after a cardiac event.

This detailed investigation by Alibhai et al. provides a rationale for modifications to the hospital environment so as to promote more normal diurnal physiology—for example, targeted alterations in the frequency of care that reduce nocturnal noise; light and disruptive monitoring may actually improve long-term outcomes. With luck, a better understanding of diurnal pathophysiology could improve treatment of a variety of acute illnesses.

F. J. Alibhai et al., Short term disruption of diurnal rhythms following murine myocardial infarction adversely affects long term myocardial structure and function, Circ. Res. 10.1161/circresaha.114.302995 (2014). [Full Text]

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