Conversation so far:
How can you tell if someone is suffering from depression?
You may be depressed if, for more than two weeks, you've felt sad, down or miserable most of the time, or have lost interest or pleasure in usual activities, and have also experienced several of the signs and symptoms across at least three of the categories below.
What are common types of depression?
he four most common types of depression are major depression, persistent depressive disorder(formerly known as dysthymia), bipolar disorder, and seasonal affective disorder.
What causes depression?
Rather, there are many possible causes of depression, including faulty mood regulation by the brain, genetic vulnerability, stressful life events,
What is the role of brain chemicals in depression?
A chemical imbalance in the brain is said to occur when there’s either too much or too little of certain chemicals, called neurotransmitters, in the brain. Neurotransmitters are natural chemicals that help facilitate communication between your nerve cells.
Does a lack of sunlight cause depression?
If you're not careful, a lack of sunlight can actually lead to a form of clinical depression
How can you treat SAD?
Treatment includes light therapy (phototherapy), talk therapy, and medications.

Question: What is the role of melatonin
Self-contained rewrite: What is the role of melatonin in SAD?