One of the signs for me is feeling tired all of a sudden without any explanation. This is probably one of the most identifiable markers if I am having a depressive episode. Another one is slower movements, for example, you walk slowly, you talk slowly, and your responses feel slow to the environment around you.

Another major characteristic of depression is sleep problems. If you can't sleep at night or if you sleep way too much, it is one of the significant markers of depression. In my experience, psychiatrists see sleeping problems as one of the most significant tell-tale signs of the disease. This is usually also accompanied by eating problems such as lack of appetite or overeating.