I found that to be true in my case. For me too much sleep = too much trouble. I try not to take naps anymore if I am dead tired. Even if I did I take only 20 mins nap. Also I don't take any medicines in the night which affects my sleep. Meds like Klonopin which stayed in my system longer messed me up quite a bit and gave me sleep apnea every morning. Amitryptyline was not that bad but made me very fatigued the next day. Not sure why I was given bcuz I didn't complain about sleep or terrible headache (only dull) in the beginning.
I even came off of Trileptal which doesn't do much. Only med works for me is Xanax and I take the minimum dosage (only in the morning/afternoon so it gets out of the system before night) which helps me to go do my things without much struggle (going to stores etc.,)
Another thing is when I eat something that also affects my dizzy feeling. Probably more blood going to stomach than brain. Even for that Xanax helps. May be my stomach acting up and this thing keeps it in check. Or relaxes some muscles? No idea.
When I have disturbed sleep (or slept only few hours in the night) next day my symptoms were not that bad. It is bizzare! I can sleep a lot if I want to without meds
but I pay a big prize next day. My PCP mentioned she has Migraine and if she sleeps too much she gets terrible Migraines.
Only way is try different things (less sleep, more sleep, normal sleep etc., eat /drink different foods, try some other meds etc.,) to rule out the problem may be.
Someone said this thing about Insanity (in a non-literal sense): Doing the same things over and over and over again and expecting different results.