Assuming you’re getting the same amount of sleep and all other things being equal… Does anyone know if there is any measurable difference in the benefits gained by working out in the morning as opposed to at night?
I don’t know if one is better, but I really prefer trianing in the PM
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Do both each day so you have your bases covered. 
I wish I could be that disciplined. Being tired from the pm workout tends to stomp out my good intentions of doing an am workout.
It’s really a personal thing when it comes down to it. Day to day stresses can effect you training either way and the only thing that may help a bit would be environmental conditions in the mornings are usually a little cooler which can have an effect on training stresses. If you are a night owl however, that can make training in the morning rather difficult.
Chris
If you have no problem getting up early, I think morning training has a slight edge. You can bank the miles more reliably in the morning.
I work out in the evenings, and sometimes I am tired from work (or didn’t eat right during the day) and end up bagging on the workout.
I’ve always rationalized that slipping quickly into recovery mode (sleeping) after working out at night was probably a good thing. But I’m an accountant so what do I really know anyway.
Runner’s World had an interesting article about the benefits of PM training this month, might want to check that out.
Lately I’ve been working out in the mornings or at lunch more. I much prefer to work out at night though. I think a morning workout is better psychologically because it’s the first thing you do in the morning so it usually gets done. If you work out at night it’s a lot easier to blow off a workout.
Don’t know any scientific data, but I workout in the evenings after work for most of the season. Only before a big race will I switch to doing some morning workouts to get the body and mind used to it.
I just find that if I try morning workouts I still get to bed at the same time so wind up losing out big time on sleep. It’s tough when the rest of your world still expects you to be up until “normal” times.
I don’t have any scientific verification but I have been hearing that morning workouts may not be the best thing, as your body needs time to get moving after sleep. I think that easy morning exercise (ie. walking) is good but you should save your more intense workouts until at least lunch or dinner time.
One advantage with mornings is that there is no reason to miss a workout, other than sleeping in.