I suspect you were craving salt because you had lost electrolytes. I know it seems like the opposite should be true since you drank salt, but when you do the salt water flush your body doesn't absorb it. The concentration of the salt in the drink is greater than what's in your blood so water is drawn out into your intestines trying to dilute the salt that's in the water you drank. That's why you get flushed out. The salt goes right on through instead of being absorbed.
As far as sleep, I like a combination of valerian and melatonin about 30 minutes before bedtime. I've also used the over the counter sleep aids. Either way, I've still gotten good flushes.