Do some research on "pulsatile tinnitus" you can get some more information about it. I have the problem also. In the left ear can I only hear it when lying down and it feels like my heart beats in my ear and shakes the pillow and my shoulder. My right ear can hear it all the time but it is more of a throbbing, whooshing sound that is rhythmic with my heartbeat. I am able to sleep though (I tune it out). It sounds awful for him, it must be a lot louder.

I had surgery on my right ear in November to fix some inner ear damage from the head injury so I don't sleep on that side, and don't know if it would feel the same as the left. I'm waiting for some more tests to figure things out. It can be an indicator of other conditions or it just could be there with nothing else going on. He may want to get things checked out by a good ENT, one who is mostly focused on the ears (neuro-otologist) rather than the nose and throat. It also wouldn't hurt to have his neck checked and adjusted by an upper cervical chiropractor (the gentle type, no snapping and cracking). If it is a blood flow issue that may help. Good luck!