user4748: 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? 

user-1: Ian,
Meditation does not necessary increase sensitivity. If it is merely a "switch off" or "ignoring" infuences training then, because of becoming used of a certain as pleasant recognised state of "defusing" it seems to have reasonable influence of the non-defusing parts of time with it's dislike.
Generally sensitifity should be trained from gross to fine and the steps are traditionally generosity, virtur and reflecting the Dhamma (dana, sila, bhavana). Then, having got valid sensibility (not in a sense of dislike), it might be proper to go into Samatha (tranquillity) meditation. In this way, by being really more sensible, it will also be easier to come and go into Vipassana later on, or even before.
If doing just a "ignoring-training", used often as well-ness tool, it naturally has it's good and it's bad, but does not really work on the cause. Like doing fitness training for compensation.
A possible useful talk on the first steps might be: Sensitivity through generosity.
[Note: This is a gift of Dhamma, not meant for commercial purpose or other low wordily gains by means of trade and exchange.]

user12260: From my experience, yes. That is obviously your experience too. When you say meditation, what type of meditation are we talking about? Mindful-meditation? Are you focusing the mind on the breath and clearing your thoughts? If so, then you are creating a vacuum in your mind. Nature abhors a void, therefore you naturally become more aware and connected to the external. 
When I was living at the Temple in Brooklyn, I shaved my head and noticed that I was even MORE connected to the external. I could literally feel the temperature of the air in the room change. Sensory overload. Oddly enough, my Sensei would go outside in the winter with no hat on. I thought, his head must be so cold. But what is cold? Cold is of the mind. You can choose not to be cold. Just as you can choose not to be overly affected by cars and the panoply of urban life. It is all in the mind.

user12005: The sights and sounds were always there. Since your question is about why it is different when you meditate as opposed to the days you don't, may be you need to understand what happens on those days in order to understand this increased sensitivity ?
Maybe your mind was caught up in worrying about fulfilling commitments, like reaching university on time. Maybe you were daydreaming, or probably just scanning the environment and only noting novel and interesting stimuli.
Probably this doesn't happen on the days you meditate. I don't know about your typical meditation session, so I am assuming you are watching the breath. So you watch the sensations that make up the breath for a period of time. You are not only looking at interesting sensations during this session, you are looking at all the sensations - if you are doing it right. So after this session, when you go out, its only natural that you are not looking at just interesting sensations or worrying about getting somewhere, but looking at all the sensations that make up the external reality.

If so, how, and what is the purpose of this with regard to meditation practice? 

You need to observe all the sensations of your meditation object for making progress in mindfulness meditation. It is normal to have some spill over effects of practice in normal life. If you can, you can maintain mindfulness while interacting with the world as well. If you can't, that is fine, as it is generally considered to be more difficult. So increased sensitivity is normal, and it is result of being open to all sensations during the meditation practice.

4748: <p>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. </p>

<p>Does meditation increase sensitivity to these stimuli? If so, how, and what is the purpose of this with regard to meditation practice? </p>
 -1: <p>Ian,</p>

<p>Meditation does not necessary increase sensitivity. If it is merely a "switch off" or "ignoring" infuences training then, because of becoming used of a certain as pleasant recognised state of "defusing" it seems to have reasonable influence of the non-defusing parts of time with it's dislike.</p>

<p>Generally sensitifity should be trained from gross to fine and the steps are traditionally generosity, virtur and reflecting the Dhamma (dana, sila, bhavana). Then, having got valid sensibility (not in a sense of dislike), it might be proper to go into Samatha (tranquillity) meditation. In this way, by being really more sensible, it will also be easier to come and go into Vipassana later on, or even before.</p>

<p>If doing just a "ignoring-training", used often as well-ness tool, it naturally has it's good and it's bad, but does not really work on the cause. Like doing fitness training for compensation.</p>

<p>A possible useful talk on the first steps might be: <a href="http://zugangzureinsicht.org/html/lib/authors/thanissaro/sensitivity_en.html" rel="nofollow noreferrer">Sensitivity through generosity</a>.</p>

<p><em>[Note: This is a gift of Dhamma, not meant for commercial purpose or other low wordily gains by means of trade and exchange.]</em></p>
 12260: <p>From my experience, yes. That is obviously your experience too. When you say meditation, what type of meditation are we talking about? Mindful-meditation? Are you focusing the mind on the breath and clearing your thoughts? If so, then you are creating a vacuum in your mind. Nature abhors a void, therefore you naturally become more aware and connected to the external. </p>

<p>When I was living at the Temple in Brooklyn, I shaved my head and noticed that I was even MORE connected to the external. I could literally feel the temperature of the air in the room change. Sensory overload. Oddly enough, my Sensei would go outside in the winter with no hat on. I thought, his head must be so cold. But what is cold? Cold is of the mind. You can choose not to be cold. Just as you can choose not to be overly affected by cars and the panoply of urban life. It is all in the mind.</p>
 12005: <p>The sights and sounds were always there. Since your question is about why it is different when you meditate as opposed to the days you don't, may be you need to understand what happens on those days in order to understand this increased sensitivity ?</p>

<p>Maybe your mind was caught up in worrying about fulfilling commitments, like reaching university on time. Maybe you were daydreaming, or probably just scanning the environment and only noting novel and interesting stimuli.</p>

<p>Probably this doesn't happen on the days you meditate. I don't know about your typical meditation session, so I am assuming you are watching the breath. So you watch the sensations that make up the breath for a period of time. You are not only looking at interesting sensations during this session, you are looking at all the sensations - if you are doing it right. So after this session, when you go out, its only natural that you are not looking at just interesting sensations or worrying about getting somewhere, but looking at all the sensations that make up the external reality.</p>

<blockquote>
  <p>If so, how, and what is the purpose of this with regard to meditation practice? </p>
</blockquote>

<p>You need to observe all the sensations of your meditation object for making progress in mindfulness meditation. It is normal to have some spill over effects of practice in normal life. If you can, you can maintain mindfulness while interacting with the world as well. If you can't, that is fine, as it is generally considered to be more difficult. So increased sensitivity is normal, and it is result of being open to all sensations during the meditation practice.</p>
