My brushes with beta-blockers have been propranolol (Inderal), nadolol (Corgard), and atenolol (Tenormin.)
All three have caused similar symptoms as your father is experiencing with just a few differences:
propranolol was the easiest because it wore off fast and I could take it morning afternoon and STILL sleep.
atenolol had me awake for a month with NEVER more than 3 hours sleep a night
nadolol has an almost INFINITE (exaggerated

) half life so when I built up the amount in my body by adding more and more every day I got to the point where I could bearly walk and it took many days to recover even after I stopped. But that one let me sleep...A LOT!
So look for the metropolol to have elements of the three I described and probably some of it's own.
It's a dreadful class of drugs to take for just uncomplicated hypertension. Consider it only with arryhtmias or angina AND hypertension. Probaly wise to ween off it when he decides to stop...maybe 1/2 dose for a week.