JennyB
The circadian rythem upset upset transiting from earlies to lates in LoCo ops ammounts to the same thing as jet lag, ie you are awake when you want to be asleep and vice versa. Its just more noticable with true jet lag since the sun is so out of phase with your body clock. In addition its sleep deprivation since its very hard to go to sleep at 8 in the evening (I dont try anymore) before an early or remain asleep when the family is getting up for school.
All is fatiguing and gets worse with age. I watched my father who was with British Caledonian and then BA on long haul suffer more and more as he got older. How I will be in ten years having already done 8 with easy only time will tell. So as soon as the boys have finished Uni its part time for me.