Cry-it-Out is NOT a Guaranteed Solution
Though some cry-it-out advocates promise a "one day miracle fix” my research has uncovered that real life families almost never report an easy result. It often takes weeks, and sometimes months, of very intense crying (and very little sleeping) for a child to succumb to sleep every night and for every daily nap, as well. This process is emotionally upsetting to parents and siblings as well as for the non-sleeping child.
If you’ve fallen into the trap of thinking that letting a child cry-it-out is a quick fix, talk to parents who have attempted that approach, or visit any web site message board for parents using a cry-it-out approach to “sleep training.” You will see messages filled with the anguish of parents who must listen to their child cry for hours, night after night after night, sometimes for many months. Even when the cry-it-out approach appears to be working relapses are com mon – a vacation, a bad cold, an ear infection, or even a busy day of missed naps or a late bedtime can disrupt the sleep process and the family must start the crying process all over again.
It is highly unlikely that "a few nights of crying" will solve a child’s sleep problems. It is possible that the nightly episodes of stress and crying will cause chaos in the home. It is also likely that crying in bed will be com e part of the child’s falling-to-sleep routine.

Many parents want to sleep train their babies and children at a young age because they are looking for convenience at bedtime. They don't want to spend a great deal of time in the evenings putting their baby or child to bed.
I believe this is an abdication of your duty and priviledge as a parent. Children aren't convenient in any way, and they need help going to sleep, most especially when they are under the age of 18 months. As a parent, you have to accept the fact that your evenings and nights aren't "your own" anymore for at least a few years.
First off heartless is a really very harsh word to use for a parent unless they are abusing their child. No one loves my child more than me and no one is responsible for her well being more than me so as a mother i did what i had to.
This blanket statement that we are all heartless and trying to get out of being a parent at night is the biggest injustice non cry it out pushers can do to any sleep deprived parents.
You know sleep deprivation is used as investigative tool, so i wonder why is sleep so important because lack of it would make you agree to things you havent done or worst yet in a parent's case harm a baby or themselves, so be careful generalizing parents.
As far as the accusation that we all do it because we are selfish and want time, i tried 8 months with my baby every thing from Sears, to Pantley to God knows what, i bought all the books, I had sleep logs, I coslept for 8 months and yet rocking, singing, breastfeeding nothing helped her, she wont nap, she wont sleep more than 45 min at one time..I had her checked she was healthy, so you tell me what was i suppose to do when i slept into PPD at 8 months...may be i was really heartless but i really dont care what other people say b/c 16 nights of 30-40 min of crying at bed time and then sleeping till 7 in the morning and being happy bubbly like she was meant to be, I would do it in a beartbeat again.
What was heartless at our house was allowing our child continual fragmented sleep - he could not fall asleep or return to sleep on his own. We spent hours in the evening trying to sooth him to sleep on some nights. It was not the time involved for us as LOVING parents, but the fact that we had a over tired stressed baby. You could not cough while giving him a bath or he would cry.
The best thing I did for my child was a little sleep training. We used graduated extinction and never left him alone for more than 10 minutes before soothing him, picking him up and letting him know how much we loved him. And the result in a matter of four days? A child who went to sleep at night with no crying and wakes up in the morning with a smile on his face. He is happier and so are we. I no longer cry at night due to watching him constantly struggle with sleep.
I accept the fact that my evenings are not my own anymore, but I relish in the happy baby and the happy household that has been created. My child cried less with this method, then with the fragmented sleepless nights that occurred due to responding to his every whimper.
I never saw this as a solution to help ME, but my child. There is no one right way, but to label a method as "heartless", I couldn't disagree more.
I agree that Cry-it-out is not a guaranteed solution, because every time we travel or every time our 14-month old gets sick, we end up hitting the restart button and having to sleep train all over again. However, when no other methods work...including going into the child's room and holding them, hoping they'll fall asleep with 30-90 minutes of cuddling...you eventually have to let them cry it out. We have had two babies in the last four years, and neither slept well at all during the first year. We are still up for hours, frequently, throughout the night with our 14 month old son. When I do go into cuddle him, sometimes that doesn't even comfort him enough to get him to sleep, and sometimes he aggressively resists the cuddling. So what's the point in holding a baby that's wrestling out of your arms, hitting you in the face, headbutting you, and hurting himself, all while depriving himself and me of sleep? My husband and I have both experienced some very dark days from being severely sleep deprived, and this has negative consequences for our family in the way of short tempers, lack of focus and depression. We decided that it's better sometimes, for the whole family, for our son to cry it out, so that we can be better parents during the day when the child is awake and more receptive to us, and aware of the nurturing.
When we have let our child cry it out, which is now often, since nothing else has worked for us, he usually wakes up with a smile, and is as cheery as any other day. He's a very sweet, social, affectionate child, except in the night, when he appears to have night terrors, which make him inconsolable to any sleep training methods.
I think Cry-it-out (CIO) has a time and a place.
If its in public at the Health Department, or Doctors office, then you should try and comfort your child out of respect for others.
I have no children, but I have asked moms about this and they say they only let them cry it out AFTER-only AFTER they have tried to comfort them, soothe, nurse/feed them, console them, lie down with them, and when all else fails, then they let them CIO. Many mommas just let them holler and scream for 5-10-15 minutes straight in the doctors office, and this is very disturbing for me. Working in the Health Department trying to concentrate and my office is near the lobby, the only relief I get is to close the door. It may seem rude but its either a 6-hour headache/migraine, or some brief relief. I have no problems with hungry babies, baby who gets a shot, or needs a change, happy baby cooes and hollers, but my first instinct to an unhappy baby is to go and hug and grab that baby. But CIO has a time and place. In public is not the place....I think most will agree....But only after you have tried....so my answer is no don't let them JUST CIO.