All these techniques can help decrease stress and pain. Of the three Tai Chi has the most direct medical applications; although it' healing effects vary depending on how severe the injury is, as those take much more skill and perseverance to repair.
Tai Chi master Bruce Frantzis had a very good anecdote to illustrate in the beginning of his book "Opening the Energy Gates of Your Body."
The Cultural Revolution caused three things to occur in China
This led to extreme shortages of medical care which threatened revolution. To prevent this, the communist party came up with a novel solution. They recruited the heads of various Tai Chi lineages, and forced them to divulge their secrets so that an effective (but easy enough to learn) National Tai Chi form could be developed, and then did everything they could to train as many instructors as possible and distribute them throughout the country.
The communist government was well aware of Tai Chi's healing powers (specifically that if someone practiced it enough most health problems would go aware). Thus they made a mandate on their extremely limited medical care. In order to be treated for a non life threatening emergency, one first had to study under a certified Tai Chi instructor and have their practicing be initialed by them. If after 3 months of certified daily practice the ailment had not gone away, the sick individual was granted access to medical care (as all medical care in the country came through the government this was the only way to obtain it). As Tai Chi was so effective in healing a multitude of medical conditions, most of the cases fixed themselves and never required a medical intervention, thus reducing the burden enough on China's medical system for it to be able to survive.
The three things I am the most familiar with Tai Chi being able to cure are Arthritis, chronic stress and lower back injuries. In all three of these, the exact efficacy of Tai Chi is largely dependent on how much the patient is willing to practice (Bruce has stated that Arthritis tends to get the best results in clinical trials since the pain from arthritis that Tai Chi relieves is enough to motivate people to practice enough to fix the condition, whereas with many other diseases the test subjects just won't bother to practice).
There is a much larger range of applications (many dealing with the spine) that are detailed in the book Tai Chi: Health for Life. As a general rule though, anything resulting from a physical malfunction in the body or the damage and deterioration of a specific place can be repaired with Tai Chi...Which is one of the main reasons elderly in China are able to maintain a complete range of mobility, functionality and vibrancy into their latter years.
Many physical therapists will subscribe gentle massages to help alleviate injury pain.
It can relieve pain, but it cannot heal tissue.
stress
The best way to sleep comfortably with an injury depends on the type of injury. In general, a pillow under the hurt body part can help relieve pain during sleep.
I wear it too. It helps relieve pain and prevent further injury. It can also provide support and help prevent injury in certain joints.
Massaging the leg from knee to hip in the morning, at night, and before trying to move the bowels is said to relieve constipation. There is also a specific Swedish massage technique that can help relieve constipation.
Bob said, "I've heard great things about acupuncture, can you help relieve my back pain using your technique?"
After an injury, craniosacral therapy may help healing and ease the headaches that follow a concussion or other head trauma.
An ice pack applied to the area where the cactus needle was can help relieve some of the pain. Be sure to remove the needles prior to applying the ice.
Yes, relaxation such as Thai Chi and Yoga are extremely good to help relieve anxiety, but any type of exercise can help remove tension in the body and also deep breathing exercises are good.
The recommended way of relieving a muscle spasm is a muscle-energy technique called reciprocal inhibition. What you do is have the person with the spasm contract the antagonist muscle(s) related to the ones in spasm. Works like a charm.
Any injury sustained to the eye should looked at by a physician before treating at home. Cold compresses applied in 10 minute intervals may help to reduce swelling. Pain medication may also help to relieve discomfort caused by the injury.