Well this is the best exercise I have ever stumbled on! It's yoga... but it's mostly laying and sleep like meditation!
Now I haven't actually given it a try yet, BUT according to this article I found on Today.com it has amazing befits in reducing stress as well as helping reduce symptoms of PTSD, anxiety and depression. I'm not a doctor of any kind so lord only knows if the claims are true, but hey anything that just entails lying down and being genitally guided can't be that bad right?
Anyways, if you want to check out the article I found about Yoga Nidra you can find that HERE and below is a video I found on YouTube that looked like a pretty good jumping off point!
Happy relaxing!