I was taking a 12-Hr Sudafed along with a Zyrtec for my allergies, but I would wake up around 3 am every night. I decided to cut the Sudafed in half, which improved my sleep and seemed to be semi effective for my nasal congestion. However, my pharmacist said not to do so because it wasn t really cutting the dose in half. All she said was, It doesn t work that way. Is that right, and what do you recommend so I can breathe AND sleep?