Pets reduce stress through a combination of physical, hormonal, and social mechanisms that researchers have measured in dozens of studies. Petting a dog or cat triggers your body to release feel-good hormones while dialing down cortisol, your primary stress hormone. But the benefits go well beyond a momentary mood boost. Pet ownership is linked to lower blood pressure, reduced heart rate, and a calmer nervous system overall.
What Happens in Your Body Around Pets
When you interact with a pet, especially through touch, your body shifts out of “fight or flight” mode and into a more relaxed state. Positive contact with a dog, for example, reduces cortisol levels and lowers heart rate. These aren’t just subjective feelings. Among people with at least one risk factor for heart disease, pet owners showed measurably calmer nervous system activity compared to non-owners: their “rest and digest” system was more active, while their stress-response system was quieter.
This calming effect also shows up in how your body handles stressful situations. In controlled studies, people with pets had smaller spikes in heart rate and blood pressure when exposed to stress, and they returned to their baseline levels faster once the stressor ended. Your pet essentially acts as a buffer, blunting the intensity of your body’s stress response and helping you recover from it more quickly.
Lower Blood Pressure and Heart Rate
The cardiovascular effects of pet ownership are some of the most well-documented benefits. An Australian study of nearly 6,000 people found that pet owners had significantly lower systolic blood pressure than non-owners, even after accounting for weight and income. A separate study of 1,179 people found that pet owners had systolic blood pressure readings averaging about 133, compared to nearly 140 in non-owners. That roughly 7-point difference is meaningful, falling in the range that blood pressure medications aim to achieve.
Research on married couples tells a similar story. In a study of 240 couples, those who owned a dog or cat had lower readings on both the top and bottom numbers of their blood pressure compared to pet-free couples. Among heart attack survivors, pet owners had significantly better heart rate variability, a marker of how well the heart adapts to changing demands. Higher variability generally signals a healthier, more resilient cardiovascular system.
The Mental Health Picture Is Complicated
Many pet owners will tell you their animal helps with anxiety and depression, and individual studies back that up. Older adults with pets report fewer psychological symptoms and better quality of life. People with serious mental illnesses often describe their pets as a key source of emotional support. The day-to-day experience of caring for an animal provides routine, purpose, and a living connection that can counteract feelings of emptiness or hopelessness.
However, the large-scale data is more nuanced than headlines suggest. A meta-analysis covering more than 142,000 participants found that pet ownership overall did not significantly reduce the risk of depression compared to not owning a pet. When researchers looked specifically at dog owners, the numbers trended slightly lower for depression risk, but the result wasn’t statistically significant. Cat ownership, interestingly, was associated with slightly higher depression rates in some studies, though this likely reflects the demographics of who tends to own cats (more often people living alone, for instance) rather than anything the cat is doing wrong.
The takeaway isn’t that pets don’t help with mood. It’s that pets aren’t a reliable standalone treatment for clinical depression. They do, however, appear to reduce loneliness and improve general well-being, which are important protective factors for mental health.
A Powerful Buffer Against Loneliness
Loneliness is one area where pet ownership shows a clear, consistent benefit, particularly for older adults. A study of 830 primary care patients over age 60 found that pet owners were 36% less likely to report feelings of loneliness, even after adjusting for age, mood, and whether they lived alone. The strongest effect appeared in people who lived by themselves: those who lived alone without a pet had the highest odds of feeling lonely, while those who lived alone with a pet fared significantly better.
This matters because loneliness isn’t just unpleasant. It’s a health risk factor associated with higher rates of heart disease, cognitive decline, and early death. For someone who lives alone, a pet provides a consistent social presence, a reason to maintain a daily routine, and often a bridge to interactions with other people (neighbors, fellow dog walkers, veterinary staff).
Pets in the Workplace
Bringing a dog to work has become more common, and the evidence suggests real benefits for stress management. Being around dogs in an office setting, even unfamiliar ones, has been shown to lower cortisol levels and heart rate. One study found that while dog owners and non-owners didn’t differ in baseline cortisol, employees who brought their dogs to work reported lower stress throughout the day compared to those who left their pets at home. The presence of a dog in a shared space can create brief moments of social connection and mental breaks that interrupt the cycle of workplace tension.
Formal Animal-Assisted Therapy
Beyond everyday pet ownership, structured programs use animals as part of therapy for trauma, anxiety, and other conditions. Veterans with PTSD who participated in equine-assisted therapy (working with horses over a series of sessions) showed significant reductions in most PTSD symptom categories after just five days. Their heart rates also dropped measurably during sessions. Similar programs use dogs in clinical settings for patients recovering from surgery, children with autism, and adults in psychiatric care.
These programs work partly because animals provide a nonjudgmental presence that lowers emotional defenses. For someone who struggles to open up in traditional talk therapy, grooming a horse or walking a dog creates a shared activity that feels less threatening than sitting across from a therapist in silence.
What About Fish and Other Pets
Not everyone can own a dog or cat, which raises the question of whether other animals provide similar stress relief. Watching fish in an aquarium consistently improves people’s self-reported mood, relaxation, and anxiety levels. However, when researchers measured heart rate and heart rate variability while people watched live fish, the physiological numbers didn’t change as clearly as the subjective reports did. This suggests that watching fish may work more on perceived stress and emotional state than on the deeper cardiovascular mechanisms that dogs and cats seem to influence through physical touch.
The type of interaction matters. Animals you can hold, pet, and physically engage with appear to produce the strongest hormonal and cardiovascular effects. But for reducing perceived stress and creating a calmer environment, even a fish tank on your desk or in a waiting room has measurable value.
One Tradeoff: Sleep
If your pet sleeps in your bed, the stress-reduction story gets a bit more complicated. A nationally representative study of U.S. adults found that co-sleeping with pets was associated with poorer perceived sleep quality and greater insomnia severity. Dogs in particular were linked to slightly worse sleep efficiency, meaning people spent a smaller proportion of their time in bed actually asleep. Cats, on the other hand, were associated with slightly better sleep efficiency, possibly because they tend to settle into one spot rather than repositioning throughout the night.
None of these effects were dramatic, and co-sleeping with pets didn’t affect broader measures of overall sleep health. For many people, the comfort of having a pet nearby may outweigh a minor dip in sleep quality. But if you’re already struggling with insomnia, it’s worth experimenting with having your pet sleep in a bed nearby rather than in yours.