Sounds like Ambien. My XH used to take it every night to help him sleep. He got so delirious some nights our son would take video of him. But once asleep he was out cold.

Sleep apnea
Low blood sugar

PP....my DH is very grumpy if woken up.

Sleep apnea. My DH is the same. Someone could abduct me from our bed and he’d sleep through it.

Definitely see a doctor, I myself suffer from sleep apnea. Symptoms sound very similar. I'm not a bit mean, until I'm sleepy. The fatigue will change your whole life.

Get his thyroid checked. It can make you extremely drowsy / sleepy and can also lead to mood changes.

He needs a full physical and sleep test before jumping to any other conclusions

So it could be a million different health problems...sleep apnea for sure but Diabetes springs to mind as well. Make him see a Dr!

Low blood sugar? I agree with everyone saying that he needs to see his doctor. This isn't normal.

Stop waking him up.

Op, the fact that he becomes mean is worrisome. He's very likely under the influence of a drug. And for all you know, he got a legitimate prescription for something which is why he passes his drug tests. I've seen it many times before.

Could also be why he's resistant to seeing a doctor. He doesnt want to get caught.

Try to convince him to take a week off work for his health and the health of your marriage. If you take away his excuse as to why he's tired...what happens? And what happens on the weekends when he hasn't been working?

Vitamin deficiency. I'm a woman but my periods were so heavy that my blood pressure dropped so low that I always needed to be in bed and couldn't communicate. By the time I saw a doctor, she was in disbelief that I could even stand.

This was a sign that my husband was addicted to prescription painkillers (oxytocin).

Benadryl?

Narcolepsy

You said recent months, so is this something that came on suddenly or was it gradual and took awhile to realize how significant the fatigue is? Did anything change in his job? There was a stretch in my job a few years ago where I was stuck doing some horribly repetitive work all day for months and it really did exhaust me. I also have a history of depression, which a few times in my life has resulted in excessive sleep + increased eating especially carbs, a few other times in not being able to sleep + very decreased appetite. Has there been weight gain or loss at the same time? What about on the weekends? I agree with getting medical input.