Q: Mac loads on grey screen and then freezes every time I open it

When I open my mac after leaving it closed for too long it makes the same sound as when I turn it on, but it loads on a grey screen with little dots on the bottom indicating it's loading and when it's done it shows were I left off last time before I closed it. The thing is that it just crashes and freezes so I always end up turning it off and on. I have to do this every morning after I leave it closed.