I have been having an argument with dh over this for the last couple of weeks, basically since I realised he was doing it 
Baby is 7 months, very mobile but not yet walking. DH has a habit of falling asleep on the sofa while in sole charge of ds, when ds is not asleep himself.
I feel this is completely unreasonable in any circumstances as ds could hurt himself in any number of ways when not being watched but dh thinks I am being completely unreasonable because he has looked after many more babies than I have (oldest of a large family) and "he wakes up if he hears a noise". I doubt this because dh is a heavy sleeper. Case in point, I once heard ds crying over the noise of the shower, on a different floor of the house and between 2 closed doors. DH was in the same room and fast asleep.
I am also a "complete bitch" for raising the point that I am right because ds fell to the floor aged 2 weeks old while dh fell asleep while holding him. DH maintains that as ds was fine and not even crying he doesn't even know if he did fall to the floor or if dh put him there (while he was asleep
) therefore that doesn't count as he may not have done anything wrong.
I however am wrong about raising this issue because dh only told me about this incident because 2 months ago ds fell off the sofa while in my care. I was not asleep, I was less than a foot away from him, I just wasn't fast enough. DH told me about it to console me because I was nearly hysterical. So now I'm a bitch for pointing out that if dh hadn't been asleep he would have known how ds got on the floor.
What has really annoyed me today though is that I am normally asleep when dh is in charge of ds (if I'm lucky I get a small lie in once a week because I insist that dh does the morning routine to give me a break) and I'm woken up by ds crying downstairs. DS wouldn't cry for this long if dh paid proper attention and fed him when needed etc instead of just leaving him to his own devices.