Get at least 8 hours sleep. Note that this means “sleep” and not “8 hours in bed” so if you read or do other activities in bed, add extra time for that stuff. I usually give extra time for my brain to stop running a mile a minute
Go to bed at the same time every night. Wake up at the same time every morning. Avoid caffeine. Caffeine can cause sleep disruptions you may not notice, even if consumed early in the day.
Get tested for sleep apnea.
I always find it hilarious that Ukraine has sunk so many ships/submarines given they have no ships of their own.