Help, my daughter can not wake up some mornings, she is a single mother, and has to be at work at 7am 5 days a week. Even with going to bed early, she will some mornings not hear the alarm clock, the phone ring, over and over, as I try to help wake her up.

Build one of those contraptions where a bucket of ice cold water dumps on your head when it's time to wake up.

She could be suffering from SAD (Seasonal Affective Disorder) and could benefit by a Dawn Simulator.

http://www.geocities.com/Wellesley/Garden/8988/sad.html

Light Therapy Products: SunUp Dawn Simulator

Dawn Simulators

If she is on a lot of stress and feeling too tired and overworked, it might make it difficult for her to get enough sleep even if she goes to bed early.
Which would make it difficult to wake up to the alarm clock.

I am the same way! I am a mother of 3 and been like that for many of years. If you find an answer let me. I can never hear my alarm clock or phone. Even my kids will try to wake me up and nothing. And if I do get up if I have been up for 3 hours all I want to do is sleep.

Another possibility, especially for armywife is sleep apnea. Your effectively choking when sleeping which is waking you up and it occurs throughout the night. You may require a machine to assist in your breathing and keep the airway open. I sleep study may be warranted.

Maybe vitamin deficiencies?
The Use Of Vitamins And Minerals In Finding An Insomnia Cure
Herbal Remedies As An Insomnia Cure

Hahaha... some of these posts are killing me.

Ask you daughter the following:
1) has she been feeling down at any point in the past two weeks? If so, how much of the time?
2) does she get less pleasure out of the things that used to make her happy?
3) has she noticed a change in her appetite? Any weight gain/loss?
4) does she have insomnia/difficulty falling asleep?

If yes to most of these, she is likely suffering from a depressive disorder. Go see the family doc. Sleep apnea would be rare, but you would notice that she stops breathing during sleep. I also recommend the bucket idea. That was a good one.