• A 2017 review looked at 24 studies—484 participants total—on heart rate variability (HRV) biofeedback and general stress and anxiety. HRV biofeedback involves receiving data on your heart rate from a device and then using breathing techniques to change your heart rate pattern. The review found that HRV biofeedback is helpful for reducing self-reported stress and anxiety, and the researchers saw it as a promising approach with further development of wearable devices like a fitness tracker.
• A 2019 review of 3 studies, with a total of 880 participants, found preliminary evidence suggesting that diaphragmatic breathing exercises may help to reduce stress. Promising positive changes were seen in mental health self-evaluations and in certain physical measures, such as cortisol levels and blood pressure.

• About 20 percent of stroke patients have anxiety at some point after their stroke. A 2017 review looked at interventions for anxiety after stroke. The review included one study on 21 stroke survivors with diagnosed anxiety. The participants used a relaxation CD five times a week for a month. After 3 months, the participants had reduced anxiety. Because there was only one small study, the overall research isn’t enough to say whether this type of relaxation technique can help people with anxiety after a stroke.

Anxiety before an operation or procedure can lead to an increase in pain levels and use of pain medicine afterwards. People who have dental anxiety may refuse or delay treatment, which can cause problems with oral health.

• A 2017 study included 159 adolescents who were randomly assigned to nature sounds, relaxation exercises, or silent rest before undergoing scoliosis surgery. The results showed that nature sounds or relaxation exercises on the day of the surgery helped to reduce participants’ anxiety before surgery.

• A 2019 study included 68 periodontal patients with dental anxiety. Patients received either progressive muscle relaxation and oral health education or only oral health education before periodontal treatment once a week for 4 weeks. The people who received progressive muscle relaxation had reduced dental anxiety and depression symptoms 4 weeks and 3 months after treatment. An earlier review (2013) on dental anxiety included 12 studies—679 participants total—on relaxation training or relaxation training combined with other treatments like cognitive behavioral therapy or graduated exposure. The review found that relaxation training increased patients’ sense of control over dental care and helped reduce dental anxiety, but it worked best when combined with repeated, slowly increased exposure to dental situations. The researchers noted, however, that many of the studies were small and poorly designed, and the study designs differed from each other.

• A 2018 review of 16 studies that included 856 people with anxiety disorders (generalized anxiety disorder, social anxiety disorder, and panic disorder) found that relaxation therapy reduced symptoms of anxiety, depression, phobia, and worry. This review found relaxation therapy to be more effective than cognitive behavioral therapy for reducing anxiety.

• Another 2018 review of 50 studies and 2,801 people found that relaxation therapy seemed to be less effective than cognitive behavioral therapy for post-traumatic stress disorder and obsessive-compulsive disorder. No difference was found between relaxation therapy and cognitive behavioral therapy for other anxiety disorders, including generalized anxiety disorder, panic disorder, social anxiety disorder, and specific phobias. The review noted, however, that most studies had a high risk of bias, and there was a small number of studies for some of the individual disorders.