I have been having a problem sleeping. As the mother of a 5 month old, you might think its her fault. Its not. She has slept thru the night since 10 weeks. My problem is that I am waking up several times a night.
I have read that quality sleep is defined as 4-6 sleep cycles, each lasting 90 minutes. If the cycle is interrupted, the cycle starts over, so you never get credit for that interrupted cycle at all.  Check out this site for a really good description of the sleep cycles and some common questions.
A chart from that site:

So, the goal is to go thru those 4-6 cycles, especially the 2 or 3 cycles that hit stage 3 and 4 sleep (the “deep sleep”).  I don’t know what time of the night I am waking up….I wear glasses and finding them in the dark, looking at the clock and noting the time seemed a bit much of an exertion when your goal is to fall back asleep as soon as possible.  But based on what BAGD has told me, I suspect I am usually waking up between 12 Midnight and 2 am. Assuming that I go to bed at 10:30 on average, I am possibly hitting those 2 stage 4 cycles.
When I wake up, I am pretty sure its not morning, but really could not tell you anything else. I sometimes think I have woken up for a good reason, like I was about to fall out of bed (sometimes true, since BAGD pushes me to the very edge of the bed), or that BAGD said something (not true). When I wake up, I am groggy and disoriented. But mostly, I am MAD. I am not aware of why I am MAD, but I am. Its a really frustrating kind of anger too, because I don’t understand it. Sometimes I cry a little.
Based on the chart provided on the website, I am getting enough sleep. I usually get 8 hours. But, since I am waking up during the deep stage 4 sleep, it doesn’t feel that way. So, how do I get more deep sleep? These are some recommended strategies:
1. Get more sun.    Spending an hour outside a day helps sleep patterns. Spring has sprung and I think this will be easier for me starting next week.
2. Fall into a rhythm. Go to bed at the same time every night. Wake up at the same time every day.
3. Sleep in a warmer room.
4. Reduce caffeine. Not an issue for me, but a good reminder.
5. Reduce stress. A nice goal, but sort of a foreign concept for someone as tightly wound as me.
I think I will focus on numbers 1 and 2. Its a good place to start.
On an unrelated note, it is reassuring to note that Pookie and Geetle, age 5, seem to be right on track ,according to the chart. They get 11 to 11 1/2 hours of sleep a night, 7pm-ish to 6am-ish. They could get more, believe me. But its their own choice, they are the first ones up every day, not BAGD or me. Also, Pookie is wetting the bed, which is likely to occur during deep sleep, so, if we were inclined to wake him up to pee in the middle of the night, we would want to do so between 8pm-9pm, 10pm-10:30pm and 11:30-12:00.
Finally, Giggles is also on track. As a 5month old, she should be sleeping 16 hours a day, weaning down to 14 hours soon. She sleeps 12 hours at night (yes, a full straight 12 hours, 7pm to 7am!), takes a 1 hour morning nap and a 2 hour afternoon nap. So, not counting car naps, she is right on track.