Daylight saving time disrupts pets' internal biological clocks, causing stress and behavioral changes.

Animals operate on a circadian rhythm, an internal 24-hour biological clock regulated by the suprachiasmatic nucleus in the brain. This system is heavily influenced by natural light cycles and consistent daily routines. When daylight saving time occurs, the sudden one-hour shift in human activity conflicts with the animal's physiological expectations for food and social interaction.Research published in the journal Applied Animal Behaviour Science demonstrates that predictability in routines reduces cortisol levels in domestic animals. When a meal is delayed by an hour due to a clock change, pets experience "anticipatory stress." Their bodies have already begun producing metabolic enzymes in preparation for a meal that hasn't arrived, manifesting as increased vocalization, pacing, or destructive behavior.The concept of "Zeitgebers"—external time-givers—explains why pets struggle with daylight saving time. While humans use artificial clocks to tell time, pets rely on external cues like their owner waking up or sunlight hitting a particular spot on the floor. Veterinarians at institutions like the Cummings School of Veterinary Medicine at Tufts University recommend a transitional approach: by shifting schedules in 10 to 15-minute increments over four to six days, owners can prevent the sharp spike in stress hormones associated with sudden routine changes.