Disrupted Sleep Schedule

My tendency to take evening naps since my parents have come home is ruining my sleep schedule.  Because of that, when I try to take my "real sleep" overnight, I am awake in bed, tossing and turning.  A few days now I have slept maybe 90 overnight.  That causes me to feel real drowsy at some point in the afternoon, at which point I have to take my lunch break in order to take a nap.  I feel really refreshed, enough to persevere through the rest of the day ... but that only gives me enough energy into the evening, where I am sleepy enough to nap again, but only for a little while.

I did it just now, yesterday/Friday night, and I am as alert as I can be at my age.  This would mean I would fall unconscious around, oh, 5 in the morning and wake up when my folks have lunch prepared.  But that ain't happening.  I have to work today/Saturday for someone who needed a sudden day off.  I'm happy to help, and by the way, I'm over 40 hours, so this is total overtime for me.  But I know I am going to crash like nobody's business at some point during the day.  And since all I am doing is typing, my brain will get real, real bored, and I might fall asleep at my desk, no joke.