What is an anabolic steroid primarily used for?

An anabolic steroid is primarily used for stimulating tissue growth, which is the correct answer. These steroids are synthetic derivatives of testosterone, the male sex hormone, and they promote the growth of skeletal muscle and increase lean body mass. Anabolic steroids can enhance muscle size and strength by facilitating protein synthesis, which is crucial for muscle repair and growth following exercise or injury.

When considering the other choices, they pertain to different physiological processes that are not the primary function of anabolic steroids. For instance, stimulating sleep involves different hormones and medications entirely, such as melatonin, which regulates sleep-wake cycles, while regulating the stress response is typically associated with glucocorticoids, not anabolic steroids. Therefore, the focus of anabolic steroids on tissue growth distinctly sets them apart in terms of their primary usage.