At night I dream of sleep

There is a note in my baby book that scares me a little. My mother wrote it in the four-year-old section:
       NO NAPS!

The fact that it was in all caps with an exclamation point only underscores the frustration and hopelessness she must have felt around the situation. I mean, children are supposed to sleep. Sleep is important. Why wasn't I sleeping? All I can say is: Sorry, Mom.

Since that time, I've never really wanted to nap as an adult. If I do lay down and sleep in the middle of the night, it means I am sick. I didn't even "nap with the baby" like you are supposed to when you are nursing. I could never quite adjust to my son's schedule.

The one time I consider napping now is after a night in which I dream of sleep.

Don't get me wrong, most nights I sleep well. I'm in bed on time in a very dark room and fall asleep relatively quickly and deeply. And that is the trouble. It has been too long since my sleep was regularly interrupted. My body got used to not waking up at the slightest coo.

So when I am woken in the middle of the night now, it is a definite shock to my system. And there are lots of reasons why I'm woken up:

• My cat. She's on a diet. And she's hungry. If I am having a dream in which there is a gentle rapping on my face, it is from her. Except, it is not a dream. She is actually nudging my face. (She has claws, but thankfully doesn't resort to them right away.)
• Unless the gentle rapping is from my son. Sometimes he can't sleep because it is "too dark," or "too light," or sometimes he thinks it should be morning already. Little taps on my arm grow stronger and stronger until I wake up. Could be worse: He tends to wake up his Daddy by a loud burst of noise.
• Bathroom breaks. My son is allowed to leave the bed to use the bathroom in the middle of the night, but he likes to tell me first. I'm not sure why.
• My husband coming to bed. I have no idea why this still wakes me up. We've been living together for more than a decade, but I sometimes still stir when he comes in.

It is after the nights of multiple interruptions (husband + son + cat) that I want a nap. But, I don't give in - just plunge ahead and maybe get to bed early the next night. I'm not worried about me, though: Part of my job as a parent is to make sure my son is getting enough sleep. Especially considering that lack of sleep is a contributing factor to childhood obesity. But how can you determine if your child is getting enough sleep, especially on the nights we have interruptions?

I've talked before about my bears having a hard time waking up in the morning. Letting my son wake up naturally is not an option with our schedule. So, I'll ask you: How do you know if your child is getting enough sleep?