I'm diagnosed with "primary insomnia," but it's controlled by maintaining a relatively strict bedtime ritual and taking some of my meds that cause drowsiness as a secondary effect before retiring.

In my experience, sleep is critical in managing depression. Also, it's possible to "sleep" all night and not awake refreshed. Part of the problem is getting good quality, refreshing sleep.

You might discuss this with a doctor, but in the vast majority of cases that's going to lead to a sleep study that will hunt for sleep apnea. Does you situation permit that?