What Causes Fatigue When Diagnosed With Severe Depression?

. I am 67 years old, I smoked tobacco for 50 years, been smoke free for 9 months, I am in general good health, never experienced sleep problems until 6 months ago when I suffered a TIA and since then I cannot stay asleep over 2 hours, constantly waking up and falling asleep again, and unable to fall back asleep after 2 to 3 episodes of sleeping and waking up. Now, I suffer chronic fatigue, I feel groggy with no motivation to do anything, have focus and concentration problems, and suffer severe depression episodes upon awakening, that last for hours at a time, until I work through them mentally realizing how unrealistic and ridiculous they are in contrast to my life. During the day, I have to take a nap after 4 to 5 hours of normal activity, if I don t, I fall asleep if I sit down, if I try to stay awake, tiredness will over power me and have to lie down to nap. I was examined by an Ortorhinolaringologist and other than a mild deviation of my septum all seems to be unremarkable I cannot lye on my back at all because every second or 3rd breath when nasal exhalation begins, I hear a pop and throat closes and cannot exhale. Sometimes I immediately exhale though the mouth and sometimes I hold my breath for a few seconds, exhale through the mouth and resume nasal breathing for one or two breaths only for the exhale occlusion episode to repeat itself. The exhale occlusion seldom happens when lying awake on my side, but it does occur while on the side position from time to time. can you comment?