Effects of night time low frequency noise and traffic noise on cortisol response to awakening

摘要

The aim was to evaluate effects of traffic noise (TN) and low frequency noise (LFN) on sleep as measured by a change of the saliva cortisol response after wake up and subjective evaluations. In the study, 12 male subjects slept during 5 consecutive nights in a noise laboratory. They were exposed to TN and LFN during two of the nights. The levels were 40dB L_(Aeq) for LFN and 35dB L_(Aeq), 50dB L_(Amax) for TN. Saliva samples for cortisol were taken directly after wake up and at 15 minutes intervals during the first 45 minutes. Questionnaires were answered in the morning and evening. The results showed a normal cortisol response to awakening after the reference night. The cortisol response to awakening after TN, and LFN was significantly different during the measurement period and the peak found at 30 minutes after reference night was significantly attenuated after nights with LFN. It took longer time to fall asleep during LFN and there was a tendency to a higher irritation in the morning. After TN, subjects were more irritated and less social in the morning, and there was a tendency to a lower sleep quality.