I Was A Patient Of Hyperthyriodism 5 Yrs Before. RAI

I was a patient of hyperthyriodism 5 yrs before. RAI was done and now i am taking thyronorm 75 mcg for last 5 years. Thyroid is well controlled. With this, i am taking Rebonik 20, serta 25 twice and prolomet 12.5 per day. After taking serta and prolomet , i feel sleepy. I am a teacher and can not afford to feel sleepy during my lecture. Kindly guide me what should i do?
Hemant Kumar Jha