I did two summers of the CG as a Guardsman in the mid-90s. Never fainted. Not even close. The question of eating breakfast was always thrown our way as most of the time it turned out that someone who fainted didn't eat breakfast that morning. There were many a night of partying done prior to parade or duty at the house. Our Snr NCOs knew this, but as long as we could properly turn out in the morning for parade, they didn't care.
It is incredibly hot in the red tunic and bearskin. One day I was on house duty when my sentry partner puked due to the heat, but carried on with his duty. The tunic is wool and has an under-liner that is "supposed" to, key word supposed to, soak up the sweat, but on hot days the sweat goes right through to the tunic.
On parade, especially in the Old Guard Division (single Division on its own that marches on the Hill with bayonets fixed), if someone looks like they're going to pass out, we usually whispered to them in order to get them talking. 9 out of 10 times this brought them back out of their daze and they were able to get through the parade okay.
