By Capt. Paul D. Rockswold, M.D., M.P.H., Navy and Marine Corps Public Health Center."Did you know that a good night’s rest is fundamental to protecting the mental and physical health of our Sailors and Marines? Although often viewed as a luxury, studies show that sleep plays an important role in preventing many chronic diseases and protecting mental health. In fact, sleep disorders contribute to, and may exacerbate, many mental health illnesses, including depression and post traumatic stress disorder (PTSD), as well as the increased risk of suicide.