I cannot comment on the sleep benefits of Ashwaganda since I was taking it for its stress reduction properties. However, in doing further research, I discovered that it poses a potential risk for individuals with thyroid problems. I happen to be one of them. Needless to say, I discontinued it. This may not be an issue for you but I figured I'd bring attention to it, just in case.
As per google:
"Ashwagandha may be beneficial for individuals with hypothyroidism by supporting hormone production. However, it can be risky for those with hyperthyroidism due to its potential to increase thyroid hormone levels. People with autoimmune thyroid conditions should also exercise caution. Always consult with a healthcare provider to determine if ashwagandha is safe and appropriate for your specific situation. "