A new study published by Swedish researchers in Current Biology in February 2014 suggests that noise-induced hearing loss may be worse depending upon the time of day that it occurs.
The cochlea, a part of the inner ear, possesses its own circadian clock. That clock is more sensitive during active phases than inactive phases. The research suggests that hearing loss sustained during nighttime hours is more likely to become permanent than the same level of damage sustained during the day.
In the experiment, researchers exposed mice to moderate noise levels during either the day or night. They then measured the mice’s auditory nerve activity to determine damage. They found that the mice exposed to nighttime noise sustained permanent damage while the mice exposed to daytime noise did not. The researchers linked the daytime mice’s abilities to heal to the circadian clock due to levels of brain derived neurotrophic factor (BDNF), a protein.
If humans have a choclean circadian clock similar to mice, then that means that people should avoid listening to loud noise at night that may damage hearing. This is especially true for concerts and other venues where loud, sustained noises may be heard.
This research may open doors to the possibility of prevention or reversal of noise-induced hearing loss in the future.
