Apnea or cessation of breathing isn't normal at any age but it can affect people of all ages from babies to older adults.
A medical exam is needed to find out the cause of the problem. It could be a form of sleep apnea that only occurs when the person is asleep. Or it could be positional from the forward bent position of the head on the neck.
There have been some reports of bone spurs in the anterior cervical spine (front of the neck) pressing on nearby soft tissues causing problems. If the bone spur gets large enough it can press on the windpipe (pharynx) or voice box (larynx). Bending the head forward would push the bony protrusion even further into the soft tissues making the problem worse.
Usually the person reports difficulty breathing, talking, or swallowing when awake. It's impossible to know what's going on without an MRI or some other form of imaging. A medical evaluation is advised as soon as possible.