Hi- my Dad is also on Tarceva and seemed very tired. The only time during his Chemo (also Gemzar) when he was not was when he took his deximethisone during chemo and the 3 days after. I requested that we have him put on deximethisone all week to improve appetitie and wakefulness and this has seemed to work for him. Friday, Sat, and Sun are usually his in bed days but since I've seen a difference in wakefulness in all three. He's only been on it about 2-3 wks (tarceva and gemzar 3-4 wks) so I'm not sure which drug is causing sleepiness with him. Just thought this might help.
My best wishes are with you, Diane