My DH was just like this. Would fall asleep at the drop of a hat. Finally got him to the Docs... severe sleep apnoea diagnosed.
People with this do not sleep properly - even when, to all intents and purposes, they are asleep.
He now wears a mask for bedtime... never snores... and sleeps well. The change is dramatic.
Sleep apnoea can be dangerous. If diagnosed, the DVLA may be told... they can monitor the hours you sleep.... using info from the computer in the sleep apnoea mask.
Since my DH has had the mask, his hours of sleep have almost doubled.
Parents-in-Law. What do/did you call them?
Gary Glitter programme Tuesday