Editors' ChoiceAnesthesiology

To Sleep, Perchance to Dream?

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Science Translational Medicine  31 Aug 2011:
Vol. 3, Issue 98, pp. 98ec140
DOI: 10.1126/scitranslmed.3003107

In the biblical story of Adam and Eve, God causes a “deep sleep” to fall upon Adam before removing his rib. An important question in anesthesiology is whether the state induced by anesthetics resembles sleep and whether general anesthesia results in a sleep debt. Although there are obvious differences between the two states, there is also growing evidence that general anesthesia can substitute for certain aspects of physiological sleep. Animal studies have demonstrated that the intravenous anesthetic propofol satisfies the homeostatic need for both rapid eye movement (REM) and non-REM (NREM) sleep. Now, Pick et al. show that inhaled volatile anesthetics commonly used in the operating room for patients undergoing surgery leave the need for REM sleep unsatisfied.

Pick and colleagues used electroencephalography and electromyography to assess sleep patterns in mice before and after a 6-hour exposure to the inhaled anesthetics isoflurane, sevoflurane, and halothane. They found a significant rebound in REM sleep after the termination of all three anesthetics, suggesting that the time spent under anesthesia was associated with the accumulation of REM sleep debt. This interpretation is further supported by the fact that the latency to enter REM sleep was shortened after anesthesia, reflecting an increase in homeostatic REM sleep pressure. In contrast, there was no increased pressure to enter deep NREM sleep in the recovery phase after anesthesia, which suggests that NREM sleep needs are fulfilled by these anesthetics.

This study supports the hypothesis that the effects of general anesthesia on sleep homeostasis are state-specific (REM versus NREM) and drug-specific (intravenous versus inhaled). As such, different anesthetic agents could be used to probe the dissociable mechanisms of REM and NREM sleep homeostasis. These data could also lead to more individualized anesthetic care for surgical patients with sleep disorders. For example, patients with obstructive sleep apnea are often sleep deprived and prone to hypoxic events during REM sleep rebound. The findings of Pick et al. will encourage further clinical study of which anesthetics best satisfy sleep need for surgical patients who are at high risk for sleep-related complications.

J. Pick et al., Rapid eye movement sleep debt accrues in mice exposed to volatile anesthetics. Anesthesiology 17 August 2011 (10.1097/ALN.0b013e31822ddd72). [Abstract]

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