The Mayo Clinic followed 1769 people in Europe and monitored their health based on 7 health markers. They concluded that pet owners were more healthy on average than non pet owners. Dog owners specifically were the healthiest of all groups. It is thought that its because having a dog prompts owners to go out, move around and play with their dog regularly.
Alexandra Horowitz, a research scientist in the field of dog cognition believes that dogs are able to use their keen sense of smell to determine what time of day it is. Smells in a room change as the day goes on. Hot air rises, and it usually rises in currents along the walls and will rise to the ceiling and go kind of to the center of the room and drop. If we were able to visualize the movement of air through the day, what we're really visualizing is the movement of odor through the day.