The sleeper stretch has become a popular method of decreasing posterior shoulder capsule tightness and GIRD (glenohumeral internal rotation deficit). Personally, I used to be a huge fan of the sleeper stretch but after doing research on the exercise I have become skeptical on its prescription for athletes, specifically overhead throwing athletes. I switched my way of thinking on this stretch because I realized that I might be doing more harm than good over time. I have two big problems with the sleeper stretch, which I will outline below.
People lose sight of other possibilities to fix GIRD
The risk for impingement
As I was saying before, the shoulder joint needs to be handled with care. If you look at the picture below of the rotator cuff you can see that there is a lot going on with the anatomy of the shoulder joint.
Interestingly, the Hawkins-Kennedy test (picture below) for shoulder impingement places the shoulder in the exact same position as the sleeper stretch. So I question whether or not it is smart to do an exercise that places the shoulder joint in the same position as injury prescription test.
Instead of doing a stretch that might place more stress on your shoulder than relief, try this stretch/myofascial release combo: trigger point arm across body stretch. To do this, get a lacrosse ball or baseball, put it against the posterior portion of your shoulder joint, and lean against a wall. After you are get in this position take your arm and perform the cross body stretch. You can play around with the position of the ball against your shoulder. If you find any tender spots hang out there for a little longer (10 seconds or so). Pictured below is Mike Reinold performing this stretch.