You settle onto the couch after a tiring day, and your cat curls up beside you, resting its head against your hand. Its warm fur and purring are familiar parts of your bond.

How that connection affects both your bodies is less understood.

Scientists in Japan looked for signs of that connection in two hormones. Oxytocin plays a role in social bonding and can rise during affectionate contact. Cortisol helps regulate the body's response to stress and its use of energy.

The study, published in iScience, found that owners with higher oxytocin tended to have cats with higher oxytocin, too. Higher feline oxytocin was also associated with fewer negative emotions and lower cortisol in owners.

How these associations arise is still unclear. Petting is one possible explanation, lead author Saho Takagi of Kyoto University told ScienceAlert.

"I think this may be because oxytocin rises in both the owner and the cat through the petting-and-being-petted interaction, and that this interaction helps to form their bond," Takagi said.