Sleep is for the ……Childless?

I was reading the woes of my lovely bloggy friend Metropolitan Mum yesterday. She has two little ones and right now they're jet-lagged, so she's up all night, not getting much sleep. (Don't feel too sorry for her, she's just returned home from St. Lucia!)
Then I thought about my own sleep patterns. I am a notoriously bad sleeper, but I can't really tell if I always have been or just since I had children (21 years in total.) Up till now, I have always lived in quiet places. I grew up in an avenue with no access for cars; the only sounds were people walking their dogs late at night and the milkman in the morning. At university (where I probably didn't go to bed till after everyone else anyway), the two off campus places I lived were also on quiet dead ends. In London I lived in a dead end in Wimbledon and then Queens Club Gardens, which is relatively quiet. Even our first house in Chicago was on a short dead end, with a dead end alley to boot, so no traffic front or back.
Now, I live near a fairly busy intersection in Chicago, where my night's sleep is disturbed by everything from sirens to late night revelers obviously unaware that normal people are in bed at 3am.
From a parental point of view however, sleep was doomed from the start. When you're married to someone who can sleep through Armageddon, you quickly learn to sleep with one ear open - listening for the crying, the whimpering, then when they're older, the throwing up, the arrival in your bedroom  with tales of nightmares or nosebleeds. It never really ends.
Just when mine were of an age to be able to deal with most nocturnal problems on their own, I had the Little Guy and it started all over again. He was a baby when we moved into our present house so I put his bedroom next to ours; if I was going to be the one getting up with him, I might as well be close by.
Now that he's also old enough to take care of nocturnal happenings (exception being last week's impressive vomit episode), I'm up with the older two again. They prowl around till the wee hours, and despite their efforts, the stair creep always wakes me up. When the Man Child goes out (now too old for a curfew, just a gentle plea not to stay out too late) he texts when he's leaving for home, (and of course I'm awake for that), then I lie awake till I hear him come in, then wonder if he's locked the door, set the alarm, switched things off etc. (He usually does.)
The Ball & Chain is constantly amazed at how tired I am most mornings. Is there any wonder?