I agree DO what is best for YOU.
Flex time would be perfect!!!! I wish you could get your sleep issues under control, but I know all too well how hard it is, even with my meds.
It sure is a great that they asked you to consider this, since it only is for a certain amount of time I would say go for it, but only you know what is best for you.
Talk to them about it, and see what they say.
Good Luck......
Hugs, Nikko