You should be extra careful during the hours of sunrise, sunset, and nighttime because

Poor visibility, difficulties in colour perception, lessened colour contrast vision due to darker shadows and reduced peripheral vision, these are the reasons why one has to be extra careful while driving during hours of sunrise, sunset and night time.

Explanation:

Sunrise, sunset and night time are parts of the day with minimal or absolutely no presence of sunlight. To safely navigate roads, we require enough light in order to detect presence of other vehicles, signs and pedestrians. Less sunlight during sunrise and sunset light the sky but makes the roads and vehicles have a darker, less bright view. The contrast between colours is the least, making it difficult to identify objects and see clearly.

A rising or a setting sun can also lead to glares on the driver's view and thus obstruct it. Since a change in ambient light is observed, our eyes need to adjust with this change and this isn't spontaneous. Night time driving has headlight glares from approaching vehicles and reduced surrounding visibility. The eyes switching for vision adaptability from dark to bright light if vehicles approach and pass by is not a quick action. Hence the driver's vision is compromised in every such case and this may lead to accidents.