I just wrote a long and detailed post and when I went to submit it I found that I had been logged out so I logged back in and then lost my post

I understand being logged out when I am not actively using the site but why while I am writing a post? It does takes me a very long time to compose a post...is there anyway to avoid this happening while I am posting or at the very least avoid losing my post if I do end up being logged off?

Thanks,

PhoenixRising55