Q:

Why is coffee comforting

I find drinking coffee relaxes me. Given that caffeine is a stimulant, I would expect it to do the opposite. Why? is it psychological? does it have something to do with it being a hot beverage? is it an effect of the caffeine? 

A:

A 2008 U. Colorado (Boulder) study*, suggests that merely holding warm drinks (vs. cold) can positively influence perception of people. 
There is apparently some connection between the physical act of holding a warm drink and one's perception of the outside world. The association of warm beverages and positive feelings may underlie the sensation of relaxation as well, although I didn't find a study on precisely on point. 
Whether the effect is physiological or psychological the authors weren't sure.     
*Experiencing Physical Warmth Promotes Interpersonal Warmth, Science, 322: 606-607 (2008) Williams and Bargh.

A:

Coffee has many compounds beyond caffeine. There are  trigonelline, proteins, carbohidrates, quinic acid, caffeic acid etc... So the chemical mix in your cup is a little more complex than just a caffeine shot. All of these chemicals are going to stimulate your sense of taste, and this effect may be relaxing, even if they are latter followed by a caffeine high. 
On the other hand you have some effects in your physiology that come from drinking a hot beverage, even if it is only hot water, the temperature change would produce an effect in your body that can be perceived. 
Your psychology may also be playing a role here, if you associate drinking your cup of coffee with a relaxing situation it may help you relax at a psyc level. 

