Validation of a novel method to interrupt sleep in the mouse.

Interrupted sleep, fragmented sleep or restricted sleep is a corollary of many psychiatric, neurological and respiratory disorders and also results from disruptive environments such as that of the intensive care unit (ICU). Recent rodent studies have revealed that sleep interruption (SI) can have more significant consequences for cognitive and neurophysiological variables than were expected and may even be equivalent to those of total sleep deprivation. Results from this research are therefore being increasingly recognized for their implications, which may include delayed recovery from critical illness in the ICU. Here we describe in detail a method for interrupting sleep in a murine model, which we had previously adopted to show an increase in mortality after septic insult. Interrupting sleep for 30s every 2 min over 48 h significantly decreased rapid eye movement (REM) and non-rapid eye movement (NREM) sleep. The technique, which is based on using a standard laboratory orbital shaker to oscillate the cage containing the mouse, can easily be adapted to use different parameters for SI. During recovery, mice exhibited a rebound in REM sleep time and an increase in the depth of NREM sleep as measured by delta (1-4 Hz) power in the electroencephalogram. The changes in sleep both during and after SI showed some differences from those previously observed in the rat using the same SI parameters. In conclusion, the mouse may provide a useful alternative model for studying the effects of SI.