Reuters Health is reporting a study in the journal Sleep that found that regular practice of tai chi, a Westernized version of the ancient Chinese martial art of tai chi, can help older people rest easier at night. Nearly two-thirds of people who learned the slow, gentle tai chi moves experienced significant improvements in sleep quality, compared to about one-third of those who participated in health education sessions that included information on how to get a better night’s rest.
My Take?
In my book, Alternative Medicine: The Christian Handbook, I say this about Tai Chi:
People who are not used to exercising should be particularly cautious and have a general checkup by a physician before starting a Tai Chi program or any exercise program. Most studies on Tai Chi are done with healthy volunteers. 
People who are ill or weakened by age or disease should be cautious about starting any exercise program. The benefits from Tai Chi may not be as apparent with unhealthy patients.
The same cautions as expressed with all other life energy therapies apply to Tai Chi. 
The religious nature and goals of Eastern therapies should not be forgotten. In attempting to introduce people to the universal energy field—and become unified with Universal Consciousness—these practices can be the door to the occult realm.
Tai Chi is frequently offered in the West as both an innocuous exercise regimen and a martial art, often with no religious aspects discussed with students. 
However, more serious practitioners are often committed followers of Eastern religions and may teach that these beliefs must be embraced to properly practice Tai Chi or experience its benefits. 
Thus, while there may be some general health benefits, Tai Chi may also bring spiritual harm.
Exercise programs have been designed for people at every point on the fitness scale and with a variety of preexisting ailments. We see no reason to adopt one immersed in religious connotations when such nonspiritual alternatives are widely available