Brain Chemistry

• According to the Depression Guide, alcohol can physically contribute to depression by affecting a person's brain chemistry. Alcohol can have an inhibiting effect on serotonin levels. Serotonin is a neurotransmitter that is linked to depression. Many antidepressant drugs work by increasing serotonin levels in the brain. Research also has shown that alcohol can affect the brain in areas that promote depression, such as interfering with sleep and appetite.
  
  

Physical Effects

• Alcohol has physical effects that can cause or deepen a state of depression. It inhibits people's motor skills, coordination and balance. Alcohol also clouds rational thinking. This, in turn, can lead to frustration and low mood as a person struggles against its effects. People often will get sleepy, and eventually pass out because of alcohol's depressive effects on their system.
  
  

Self-Medication

• The Depression Guide notes that people who are depressed frequently turn to alcohol in an effort to self-medicate. They seek the initial pleasant feelings brought on by intoxication. Once those feelings pass, however, alcohol can suppress their mood and make them tired, irritable and disoriented. This feeds into their cycle of depression, and intensifies it. People also may feel guilty about their drinking behavior, which can compound their symptoms of depression.
  
  

Medication Mixing

• Alcohol is classified as a sedative hypnotic, and many prescription medications that treat depression fall into this category as well. Because alcohol damages the liver, which inhibits the processing of toxins, drinking can inhibit or amplify the side effects of these drugs. Mixing antidepressant drugs with alcohol can increase the symptoms of depression, and in extreme cases, cause death.