Instantaneous change in sleep stage with noise of a passing truck.

The transient effects of passing truck noise on sleep polygraphs of 8 men were studied. The percentage of the sleep Stage 2 which changed from Stage 2 to Stage 1, waking or movement time, was calculated. The shallowing of REM sleep was identified when it had changed to other stages, and the shallow epoch percentage was calculated for the REM sleep. The percentage of shallow epochs for Stage 2 significantly increased against that of the control condition after exposure to noise but was not statistically significant for Stage REM. In conclusion, the shallowing or changes in the sleep Stage 2 or REM sleep with the passing truck noise might be observed at noise levels of less than 45 dBA or greater than 60 dBA, respectively.