A depressed person may not seem sick in the same way that someone with a disease like cancer or diabetes seems, but the behavioral health condition is a legitimate illness that can have an impact on a person's work attendance. In fact, nationwide, depression may cause more lost workdays than most major illnesses [source: University of Michigan Depression Center]. And it's the No. 1 cause of disability in the United States [source: National Alliance on Mental Health].
Calling in sick to work is a behavior that can be influenced by many other depressive behaviors. For example, the isolation caused by seeking out fewer activities with family and friends could possibly make a person less likely to want to interact with co-workers. The aches and pains caused by depression may make someone feel physically ill and, thus, justified in calling in sick. And, of course, oversleeping or not sleeping enough may make keeping a consistent work schedule problematic.
Symptoms of depression, and the behaviors they cause, don't occur in a vacuum. They're connected, and they feed off of each other. The best way to change them is for the depressed person to seek treatment for his or her overall depression. He or she can then address individual symptoms or behaviors under the guidance of a doctor or therapist.