I think it depends on the person. If I do exercise before bed then it makes more more awake, not less. However, I know some people that it really helps!

When you say, you have your drink before bed and your body associates that with sleep time, I think that's really true. Having a routine before bed will really help get your body ready for sleep. Perhaps your body associates exercise with getting ready for bed because it's your routine.

Because I normally exercise in the morning I associate exercise with waking up! So the key that you've identified is the routine :D And I think that's exactly right!