I have seen stats that say mornings are the worst time overall for depression in depressed people. And there is a particular form of depression called diurnal m

I have seen stats that say mornings are the worst time overall for depression in depressed people. And there is a particular form of depression called diurnal mood variation where people are depressed in the morning then fine later in the day. So I agree it's likely a biological thing first and foremost. When people are depressed they tend to find negative things to focus on, perhaps in an attempt to explain the pain, so I'd think the guilt over oversleeping is more of a side effect.