Persson Waye, Nighttime Low Frequency Noise Effect on Cortisol Response..
Effects of nighttime low frequency noise on the cortisol response to awakening and subject sleep quality
Kerstin Persson Waye, Angela Clow, Sue Edwards, Frank Hucklebridge, Ragnar Rylander, 2002
Elsevier Life Sciences
The auditory system is permanently alert, even during sleep. Excitations of the system are subcortically connected via the amygdala to the HPA axis. Thus, noise can influence the release of different stress hormones, especially in sleeping persons during the early morning phase. Increased urinary cortisol levels collected in the morning have previously been found in humans when exposed to nocturnal aircraft or road traffic noise during sleep and among children exposed to more than 60 dBA, day and night weighted.
While the effects on sleep and well being of transportation noises are rather well documented much less is known of effects on sleep caused by low frequency noise (<200 Hz). Low frequencynoise is common in both occupational and domestic environments. Several case studies and some epidemiological studies indicate that low frequency noise affects sleep quality, particularly with reference to the time taken to fall asleep and tiredness in the morning