I have recently been taking 30 mg of Mestinon at approximately 8 am 12 pm and 4 pm - I can fall asleep at about 9:30 on this schedule.

Sometimes I get a late start on my first pill, and since I have to wait 4 hours between, my last dose has been as late as 5 or 6 pm - this is too late for me since this puts the time I am able to sleep at 10:30 or 11:30. And then I wake up late in the morning and it is hard to get my earlier schedule back.

The odd thing is that when I take a 4th dose, in order to be able to function past 8 pm, then I don't sleep well all night. I am able to go to sleep at about 1 am, but I wake up early at about 5 am wide awake.

I didn't realize the correlation between my sleep habits and the Mestinon until I started keeping records.

I did find that if I take the pills at 6am, 10 am & 2 pm, I am more easily able to take a 4th dose occasionally at 6 pm and sleep relatively well. I prefer this schedule since I wake up with the sun but the sun is not shining at 6 am these days. Soon the winter solstice will be here and the days will get longer again. Hooray!

My answer got longer than I intended...Here is the short answer: The absolute latest I like to take Mestinon is 6 pm, but for best sleep the last Mestinon should be about 3 pm for me.

I hope your sleeping improves.