Safari tabs keep closing overnight

Hi there,

I hope someone can help with this issue. I'm sure it must be a simple setting but I can't find it!!!

My safari keeps shutting down overnight.

In the past, if I had open tabs minimised in my dock, they would stay there for a long time.

Now, in the morning, I have to open safari for the tabs to re appear.

Not a major issue, just a bit annoying considering it never used to happen.

Anyone got any ideas??

Any help / advice much appreciated.

Many thanks.