Somebody gave this to my daughter after the birth of her son. Fortunately
her Dad is a pediatrician and her mom teaches parenting classes so she grew
up knowing better. First off you should never try to get a 4 month old to
sleep through the night. Even Dr. Richard Ferber, the most well know
advocate of sleep training doesn't recommend starting it till the child is
at least six months old. If it comes naturally to them, fine, but at that
point in their development most children need to wake and nurse both for
physiological and emotional reasons. If you really want to know more about
this I suggest reading What's Going on in There? : How the Brain and Mind
Develop in the First Five Years of Life. But as my husband tells his new
patients and I tell my classes: worry less about reading books than about
reading babies.
Secondly while the "progressive waiting" method is one of the accepted
methods for sleep training, you should not just automatically increase the
spacings. To quote the person most incorrectly associated with blindly
advocating this method (Dr Ferber again): "Simply leaving a child in a crib
to cry for long periods alone until he falls sleep, no matter how long it
takes, is not an approach I approve of. On the contrary, many of the
approaches I recommend are designed specifically to avoid unnecessary crying
." If you read Ferber's book it is far more about setting up a routine (
during the day and night) than the dreaded, leave-the-baby-in-the-crib-
crying step. Ferber doesn't recommend "cry it out" because it's not healthy.
To over simplify: a frightened, crying baby produces excess cortisol. Too
much of this impacts neurological development. A four month old isn't crying
to tick you off. They're crying because they need you. If they're hungry,
feed them. If they're lonely, nurture them. You can't spoil them, the
circuitry isn't even there for that. It's not called spoiling, it's called
parenting.
We've become a people addicted to connivence, but raising happy healthy
babies will never be convenient. No $20 device is going to help you be a
better parent. Trust your instinct, trust your baby, and use the brain God
gave you to find the balance between healthy amount of sleep for parents and
baby, and a healthy amount of nurturing too. I've had six kids. One slept
through the night after three months. One after 18 months (he woke up to
nurse constantly - now he's 6' 4" and still snacks late at night!). Most of
the rest fell somewhere in-between. In the end I managed to pack them all
off to college. Relax, trust yourself, and you and the baby will figure out
this sleep thing eventually.