When should cruise control not be used while driving?

Cruise control should not be used when a driver is tired because it can contribute to decreased alertness and slower reaction times. When a driver is fatigued, their ability to respond promptly to changes in traffic or road conditions diminishes. Using cruise control in this state may lead to a false sense of security, making the driver less engaged and more prone to making errors. It is critical for drivers to maintain full attention and control of the vehicle, especially when they are feeling tired, to ensure their safety and that of others on the road.

Other scenarios, like driving in heavy traffic, on steep hills, or during adverse weather conditions, also present challenges for cruise control usage, but the issue of driver fatigue directly affects the driver's attentiveness and decision-making ability, making it particularly crucial not to utilize cruise control in such circumstances.