FWIW, I was told to split up my BCP and thyroid med, Blueberry. I assume that's because some studies show that estrogen can inhibit uptake of the Lexothyroxin. When I first started taking it, I took my BCP in the morning. I switched that to my 10 pm bedtime, and took my Synthroid in the middle of the night (usually around 3ish).

If anyone does change the timing of their dosage, make sure that you get your levels rechecked. As Grits' experience suggests, it could potentially lead to overmedication, especially for those who are already withing a normal range.