Just like rickzee says, it' a medical sign that needs attention NOW. The sign of 'sleep apnea disorder' is, maybe, what's wrong, Bricam, and, I just say to see a doctor with your dad, be his support, the Lord leads.
Sleep apnea is where a person is sleeping and suddenly starts choking in their sleep and cannot wake up and will die in their sleep, this happened to my uncle last summer and to another friend the summer before.
I cannot stress this enough, please, take your dad to see a doctor, they can give a prescription for medicine to help the disorder.
It is what JK, rickzee, say, the Enemy does attack us in so many ways and he has attacked your dad. Satan is stong, but God is stronger. On our own, Satan will win EVERY time, but, with God, we are STRONGER. Just like JK says, Goliath was strong, David was weakling, but God WAS stronger, David won
Put your trust in Him and also have your dad pray for bringing this sickness out of himself through faith in Him and believing in the almighty healing POWER of God, for with God all things are possible IF we only believe. The Lord leads us and we are to follow, now God has this ailment in your dad's life but God's power and striking down the Enemy 'in the name of Jesus,' YOU will more than CONQUER this sleeping nightmare ordeal your dad is going through. Praying for you, brother, God is good. And, never forget, He is 'great,' too, for great is the Lord and worthy of glory, and, great is the Lord, worthy of praise, NOW, lift up your voice, LIFT UP YOUR VOICE.
Gr-e-e-e--e-at is the Lord
The boldness of asking God for prayer, for ourselves, for others who are a part of our life, for others who are not, even, is great