In many ways they can actually provide substantial benefit. The frames of eyeglasses and sunglasses intrude far more into the peripheral visual field than any properly fitted and certified helmet. Eyeglasses are not known to contribute to accident causation, except perhaps in their absence. More importantly, a helmet does not prevent a rider from turning his or her head from side to side to observe traffic. Eye protection is especially important in accident prevention because a rider can see more clearly without tearing from windblast, or injury and distraction from dust, dirt and debris thrown up by other vehicles on the road.
Helmets cause overheating.
Helmets themselves do not cause overheating. Riders should also recognize that in certain climates it could be too hot to ride. But then it's also too hot to walk, drive, work or be involved in any kind of physical activity comfortably. A study showed that while the surface of a helmet can get quite hot, the temperature inside a properly fitted helmet rarely rises more than one or two degrees above body temperatures. For the most part, temperatures tend to stabilize at or near body temperature.