Short Answer 
The extreme day and night cycles at the poles, caused by Earth’s axial tilt, result in phenomena known as polar day and polar night, where certain regions experience continuous daylight or darkness for extended periods. Countries such as Norway, Sweden, Finland, Russia, Canada, and Greenland are affected, leading to adaptations in daily life, agriculture, and wildlife behavior due to these unusual light patterns.
Step 1: Understanding the Phenomenon
The extreme day and night cycles occur due to the tilt of the Earth’s axis, particularly in the polar regions. This phenomenon is categorized into two main aspects: polar day and polar night. During polar day, the sun remains visible for 24 hours, resulting in endless daylight. Conversely, during polar night, the sun does not rise, leading to continuous darkness.
Step 2: Identifying the Affected Countries
Several countries located within or near the Arctic Circle experience this unique phenomenon. Specifically, these countries are:
- Norway
- Sweden
- Finland
- Russia
- Canada
- Greenland
Each of these countries has regions that can witness six months of continuous daylight followed by six months of continuous darkness.
Step 3: Grasping the Impact on Daily Life
The extreme variations in daylight affect numerous aspects of life in these regions. Residents experience unique challenges and advantages, such as:
- Adaptations in daily schedules due to prolonged daylight and darkness.
- Impact on agriculture, making certain crops easier to grow during extended daylight.
- Changes in wildlife behavior, as animals adjust their activities according to light patterns.
These extremes in daylight and darkness provide both distinct experiences and challenges for the inhabitants of these regions.