Some fiddles will readily accept variant tunings, while others won't. Those I've had didn't like to be messed about with, and would sometimes take days to settle down after being forced outside what they were used to. It's probably best to keep a second instrument for scordatura tunings.

When I wake up in the morning, my muscles are inflexible and weak; also I can hardly speak. After a little while, the blood starts to circulate with exercise and gets better oxygenated; I can move more easily and my voice comes back. Violins are exactly the same (though they are less inclined to hangovers, perhaps); they need some exercise before they wake up properly, especially if they sleep for long periods between outings.