I wish they'd decide to have either GMT or BST (in the UK) and then leave it alone!! I too am wiped out today, after even less sleep than usual on a Sunday night (never sleep well on Sundays before work!). And, as someone who gets up early (0530!), I'd just got nicely used to getting up and going to work in daylight, and now it's dark again!! Like you say - it doesn't 'save daylight' - there's a finite amount of daylight no matter where you put it in the 24 hour period!!
I don't have a problem with using BST (so having the long summer evenings), but I really can't see any real advantage to changing it. All it does is mess us all up twice a year!!