When should cruise control not be used while driving?

Cruise control should ideally not be used when you are tired. This is because fatigue can significantly impair your ability to react quickly and make decisions while driving. Keeping a firm and alert control over the vehicle is essential to ensure safety, especially on the road where unexpected situations can arise. When utilizing cruise control, a driver might become too relaxed, potentially leading to slower reaction times if fatigue sets in. Maintaining full engagement in the driving process is crucial to reacting appropriately to hazards, ensuring that you remain aware of your surroundings and can take immediate action if needed.

In contrast, while it is advised to avoid cruise control in heavy traffic, on steep hills, and during adverse weather conditions, these scenarios primarily focus on maintaining control and adaptability to different driving conditions rather than the driver's physical state, as in the case of tiredness.