My dr told me that getting more than 8-9 hours of sleep every night trains your brain to make you depressed. why is this?

Sleep and Mood: I think most of us WOULD NOT agree that sleeping 8-9 hours at night trains our brain to experience depression. Are you sure that's what you were told? Each person requires a different amount of restful sleep at night, normally 7-8 hours. Excessively sleeping less or more than this could represent a number of illnesses, or behavioral conditions. Excessive sleep may indicate a mood problem.