Introduction
The soothing, rhythmic sound of a cat purring is a beloved and well-known feature of cat ownership. Many cat owners report feeling calmed and soothed when hearing their cat purr, describing it as a comforting, healing sound. But is there any scientific evidence that a cat’s purr can actually provide pain relief or other health benefits for humans? This article will explore the evidence behind the popular idea that a cat’s purr has healing properties, including the possibility that it reduces pain, inflammation, and stress in humans.
What is Purring?
Purring is a low, rhythmic, vibrating sound that cats make when they are content and relaxed. It is produced by rapid vibrations of the vocal folds and results in a low rumbling or rolling sound during inhalation and exhalation 1. The frequency of purring ranges between 25-150 vibrations per second 2. This frequency falls in the 20-140 Hz range that has been shown to have restorative effects in humans.
While domestic cats purr the most frequently, big cats like lions, leopards, and tigers also exhibit similar sounds when content. However, the major difference is that big cats can only purr during exhalation while domestic cats purr during both inhalation and exhalation 1.
Purring Frequency
A cat’s purr has a frequency range of between 25 and 150 Hertz according to The Secret Power of a Cat’s Purr. The average domestic cat purrs at 25 to 150 Hertz (Hz) as noted in this article about the magic of purring. Humans can hear sounds ranging from about 20 to 20,000 Hz, so most people can hear a cat’s soothing purr.
Theories on Purring
There are several main theories about the purpose of cat purring:
Comfort signaling – Purring may serve as a signaling mechanism for comfort and contentment. Kittens purr to their mothers when nursing, and cats may purr during petting to indicate positive feelings (https://www.scientificamerican.com/article/why-do-cats-purr/).
Healing – There is some evidence that the frequencies in cat purrs may have healing effects. The 25-150 Hz frequencies may promote bone growth and help heal injuries (https://www.wired.com/story/everyone-was-wrong-why-cats-purr/).
Communication – Purring may serve as a friendly greeting or signal of intent between cats. It can indicate a desire for food or social interaction (https://www.science.org/content/article/how-do-cats-purr-new-finding-challenges-long-held-assumptions).
Self-healing – The act of purring itself may have self-soothing effects for cats, releasing endorphins that relieve pain and stress (https://www.wired.com/story/everyone-was-wrong-why-cats-purr/).
Purring and Healing
Research has shown that a cat’s purr frequencies can have therapeutic effects, including promoting healing. Specifically, the 25-50 Hz frequencies in a cat’s purr fall within the range that can improve bone density and promote fracture healing, according to Scientific American. These low, rhythmic frequencies may physically stimulate cells and tissue to regenerate and repair themselves.
Studies have also found that exposure to frequencies between 25-150 Hz can provide pain relief, aid muscle relaxation, and reduce swelling and joint stiffness, which can facilitate healing. The soothing, low frequencies in a cat’s purr have been associated with reduced anxiety, lower blood pressure, and an overall calming effect, which can also support healing and recovery.
While more research is still needed, the evidence indicates that a cat’s unique purring abilities can have measurable therapeutic effects on humans. The frequencies transmitted through purring may physically stimulate healing, while also reducing stress and creating a calming environment conducive to recuperation.
Purring Reduces Stress
Numerous studies have shown that a cat’s purr can help reduce stress and lower blood pressure in both cats and humans. The sound frequency of a cat’s purr falls between 25-150 Hertz, which overlaps with the frequencies that can promote tissue regeneration and healing in humans (Source). It is believed that these purring frequencies may have a similarly calming effect, reducing stress and anxiety.
One study found that when humans listened to recordings of cat purrs, they showed significant reductions in systolic and diastolic blood pressures, indicating a relaxed state (Source). Stroking or petting a purring cat can enhance these calming effects. The sound vibration paired with the tactile stimulation is thought to trigger a decrease in stress hormones and an increase in oxytocin, helping create a sense of peace and wellbeing.
Less Pain with Purring
Several studies have explored the potential for cat purring to reduce pain sensation. One study published in the Journal of the Acoustical Society of America in 2001 found that the frequencies in a cat’s purr, between 25 and 50 Hertz, fall in the range that can promote tissue regeneration and repair [1]. Specifically, these low frequencies may induce a “purr-induced restorative” effect that helps relieve muscle stiffness and promote bone growth.
A 2006 study also demonstrated that sound frequencies between 25-140 Hz stimulated increased bone density and promoted fracture healing [1]. The researchers proposed the theory that cats may purr as a self-healing mechanism, especially when injured. The ability of purring to reduce pain sensation may be related to release of endorphins or reduced muscle spasms.
While promising, more research is still needed to fully validate these initial findings on purring and pain relief. Some studies have relied on small sample sizes. However the existing evidence does suggest purring may have therapeutic potential for pain management.
Possible Explanations
There are a few proposed mechanisms for how a cat’s purring may help reduce pain:
One theory is that the frequencies of feline purring (25-150 Hz) may have healing effects. According to a study published in Bioacoustics, the specific frequencies in a cat’s purr overlap with the dominant frequencies in human speech and those that have been shown to improve bone density and promote healing. The vibrations may stimulate muscles and bones at the cellular level.
Another idea is that purring may activate a rest-and-digest response through the vagus nerve, reducing stress and anxiety. The rhythmic nature of purring can produce a calming effect similar to meditation. Lowering stress can in turn dampen pain signals.
There is also speculation that purring may release endorphins in humans. The soothing, repetitive nature of the purr could trigger a release of natural pain-relieving hormones. This could create a mild sedative effect that makes individuals perceive less pain.
While interesting theories, more research is still needed to understand the precise mechanisms behind how a cat’s purring may influence pain in humans.
Criticisms and Limitations
While some studies suggest purring may provide pain relief, more research is needed. Some key limitations of research on purring and pain relief include:
Small sample sizes – Many studies have looked at only a handful of cats purring. Larger studies are needed for more definitive conclusions.
Lack of control groups – Most studies observe purring’s effects but do not compare to a control group not exposed to purring. This makes it hard to isolate purring as the reason for pain relief.
Self-reporting – Studies often rely on self-reported pain ratings from human participants, which can be subjective. More objective pain measurements would strengthen results.
Varying methods – There is no standardized way to measure purr frequencies or volumes. Differences in methods can make comparing studies difficult.
Unclear mechanism – While some hypotheses exist, the biological mechanism behind how purring might relieve pain is still unknown.
Anecdotal evidence – Much of the belief in purring’s pain relief stems from anecdotal reports. More quantitative, controlled studies are required.
Species differences – It remains unclear if cat purrs relieve pain in species besides cats or humans. More research on other animals is needed.
Overall, while intriguing, there is still limited quality evidence that cat purring provides real pain relief. More rigorous, controlled research is required to demonstrate this effect and understand the underlying mechanisms.
Conclusion
Throughout this article, we have explored the intriguing link between cat purring and pain relief. While more scientific research is still needed, the existing evidence suggests that cat purring may offer a variety of health and healing benefits for both cats and humans.
Studies have shown that purring frequencies may stimulate self-healing mechanisms and promote bone density. The sound vibration and frequencies of purring have been associated with reduced stress, anxiety, and pain levels. In humans, exposure to recordings of cat purrs resulted in observable improvements in muscles stiffness and flexibility. There are also documented cases of cat purrs easing chronic and postoperative pain.
While the exact mechanisms are not fully proven, leading theories point to the low frequencies of purring creating soothing vibrations that have therapeutic effects. The rhythmic pattern of purring may physically stimulate healing while also releasing endorphins that relieve pain and calm the nervous system.
More research is needed to determine the direct causal relationships between cat purring and pain relief. However, the evidence so far indicates that the unique vocalization of purring may convey measurable mental and physical health benefits for cats and humans alike.