Bicycle helmets undoubtedly protect users from brain injuries. But is it possible, as some studies have suggested, that the helmets make you hot and sweaty and distracted and thus increase the chances of an accident? This idea has been picked up by some who oppose mandatory helmet laws.
Some scientists decided to look into it. Based on a controlled laboratory study of 19 participants, they concluded that while the helmets were uncomfortable and raised temperature, these negative effects were not significant.
Helmet-wearing was associated with reduced comfort (p = 0.001) and increased temperature perception (p < 0.001), compared to not wearing a helmet. Just one out of nine cognitive parameters showed a significant effect of helmet-wearing (p = .032), disappearing in a post-hoc comparison. These results resolve previous disparate studies to suggest that, although helmets can be uncomfortable, any effect of wearing a helmet on cognitive performance is at worst marginal.
I was a bit surprised as to how they could get such stringent statistical limits based on so few participants in the study.
But still, wear your helmets, folks. It could save your life.