Cats yowl at night mainly because they are naturally more active during dawn and dusk (crepuscular), which can lead to nighttime activity that disturbs human sleep. Other common reasons include boredom or loneliness, seeking attention, feeling trapped if kept indoors, health issues such as overactive thyroid or kidney disease, aging-related cognitive dysfunction, and mating behaviors. Yowling is a way cats communicate needs or distress, so it is essential to consider their environment, health, and social needs to manage the behavior effectively.