"I think it makes me more alert," said Holly Craft-Moreno, a coffee drinker. "It gives me some energy and a little quick boost."
"I just have to have it," said Rosie Ware, a coffee-drinker. "It's a habit every day."
But could these feelings of being more alert and on top of their game be all in their heads?
British psychologists studied about 400 caffeine drinkers. Those who drink about four cups a day appear to develop a tolerance for caffeine.
Kaiser Permanente endocrinologist Dr. Shireen Fatemi agrees with the study's finding.
"But truly studies show that if you drink it all the time then you are just habituated to it," said Dr. Fatemi. "You don't get any buzz."
This may come as a shock to some, but researchers say caffeine did not give a boost to occasional drinkers.
"When you drink coffee occasionally you don't get the buzz," said Dr. Fatemi.
"I'm just shocked that it actually doesn't give the non-coffee drinker a real boost," said Moreno.
Study authors say some people in the population carry the ADORA2A gene. These folks tend to be more anxious anyway. So that edgy feeling they think they get from coffee may not be the caffeine at all.
"Some people are attributing certain effects to the caffeine that may not be solely due to the caffeine," said Dr. Fatemi.
So if it's all in our head should we try to cut back?
"Maybe I will cut back on coffee and see how it goes," said Moreno.
"I don't think I will stop," said Ware.
Dr. Fatemi says if you're drinking four cups or less and it's not interfering with your sleep or causing any other ill health effects then enjoy it.
Researchers also found when compulsive coffee drinkers start avoiding caffeine alertness is reduced and they tend to get headaches. When they resume drinking coffee, it brings them back to what they consider normal.