Does your world appear completely unbearable until you’ve had that first cup of coffee in the morning? Do you need a java jolt just to deal with your day?

Science now indicates you may actually need caffeine to ward off the blues. Researchers are finding that drinking caffeinated coffee decreases the risk of depression in women. And the more coffee you drink, the better.

We know that coffee is the most popular drug. According to a study in the Archives of Internal Medicine, caffeine is the most frequently used central nervous system stimulant in the world. Approximately 80% of caffeine consumption is in the form of coffee.

Depression is a chronic and recurrent condition. Previous research, including one prospective study among men, suggested an association between coffee consumption and depression risk. But women are more likely to be affected. In fact, depression strikes twice as many women as men, including approximately one of every five U.S. women during their lifetime.

Researchers from the Harvard School of Public Health examined whether consuming caffeine or certain other caffeinated beverages is associated with depression risk in women. They studied 50,739 U.S. women who participated in the Nurses’ Health Study. Participants, who had a mean age of 63 and had no depression at the start of the study, were followed for 10 years.

Researchers measured caffeine consumption through questionnaires focusing on how frequently the women consumed caffeinated and non-caffeinated coffee, non-herbal tea, caffeinated soft drinks (sugared or low-calorie colas), caffeine-free soft drinks (sugared or low-calorie caffeine-free colas or other carbonated beverages) and chocolate.

The authors defined depression as reporting a new diagnosis of clinical depression and beginning regular use of antidepressants in the previous two years. During the 10-year follow-up period, researchers identified 2,607 new cases of depression.

When compared with women who consumed one cup of caffeinated coffee or less per week, those who consumed two to three cups per day had a 15% decreased risk for depression.

And depression risk dropped in a dose-dependent manner. More caffeine dropped the risk even further. Those consuming four cups or more per day had a 20% decrease in risk. Compared with women in the lowest (less than 100 milligrams per day) categories of caffeine consumption, those in the highest category (550 mg per day or more) had a 20% decreased risk of depression.

It does seem that the caffeine in coffee makes the difference. No association was found between decaffeinated coffee and depression risk.

Other research shows coffee kills pain and sharpens your mind. It may also ward off skin cancer and lead to a longer life.

But caffeinated coffee may not be appropriate for pregnant women.

The authors wouldn’t claim their study “proved” caffeine or caffeinated coffee reduces the risk of depression. They said it only suggests the possibility of such a protective effect. They called for more studies.

In the meantime, go ahead and enjoy a guilt-free, uplifting cup of coffee.