Does meditation increase sensitivity to sense perceptions and why?

Each morning, I meditate for 30 minutes. Within 45 minutes to an hour after, I commute to my university. For the first hour or two that I am at university after meditating, I feel almost overwhelmed by the intensity of external stimuli (car noise, sights, sometimes even internal thoughts and physical feelings). Conversely, on days that I do not meditate, I feel relatively stable and at ease walking onto campus. Does meditation increase sensitivity to these stimuli? If so, how, and what is the purpose of this with regard to meditation practice?