Does the position you sleep in affect your sleep?

Yes. In around 30% and up to 50% of the time sleep apnea and snoring improves when the person is not on his/her back. Therefore, sleeping on the side may improve the sleep quality if the person has positional sleep apnea. Pain associated with certain conditions may get better or worse with certain positions. Pain affects the quality of sleep.
Maybe. Human growth hormone (hgh) is particularly released during delta phase of sleep, the deepest sleep level. In an adult, hgh is involved in many pathways involved in maximum tissue and organ performance and minimizes age related breakdown. Remember, it is not necessarily total sleep time but more so the quality and level of delta sleep levels that may be at play.