Blood pressure, respiration, and muscle tension all increase on initial exposure to red. But, this jazzy hue also boosts spirits and stimulates creativity, conversation, and the appetite (which is why it is used in many restaurants). Red is also a popular color in casinos—people are more likely to gamble in a red environment than in, say, a blue one. Rooms with a lot of red feel warmer, heavier, and time seems to pass more slowly in them. Red may increase passion, but also aggression, anger, and restlessness—it's probably not the best choice of color for a bedroom. In clothing red conveys energy, power, and leadership, but can also signal romance and sensuality, depending on the garment.
An interesting note: when you have two objects of identical shape and weight, one red and one blue, most people will think the red one is heavier. (Might be one reason to rethink that red wardrobe! On the other hand, red accents could perk up your image.)