- Fifteen morbidly obese patients with Sleep Apnea Syndrome (SAS) were studied during nocturnal sleep before and between 2 to 4 months after a weight reduction surgery. Six patients were also recorded between 4 to 8 months after surgery. Postoperative recordings revealed a dramatic reduction in the sleep apnea index and an improvement in sleep motility and daytime vigilance levels. A further decrease in apneas and sleep motility was seen in the late post-treatment recording. These results indicate that weight reduction surgery is an effective definitive treatment for obesity associated SAS.