The phrase "disturbed sleep patterns" means that someone's normal sleep routine is being interrupted or disrupted in some way, which can make it difficult for them to get a good night's rest. Full definition
The study's findings (that regular yoga practice can effect statistically significant improvements in sleep habits) back up a growing number of medical professionals» emphasis on altering our routines, as opposed to taking pills, to correct disturbed sleep patterns. (yogauonline.com)