"Gentle" parenting or sleep training is making the rounds as an "it" thing, but is all of it actually gentle? Sadly there are too many wolves out there dressed up as sheep and it's up to us to identify the real gentle help from the pretend stuff.
The dismissal of the importance of a rise in cortisol on the developing brain is very popular with extinction sleep training apologists. Although we do not know the exact influences, there are reasons to be cautious of this dismissal, which ignores key evolutionary and biological information.
The premise behind extinction sleep training is that infants (and toddlers) are being taught to "self-soothe"; however, this ignores key points of what self-soothing abilities can be expected from children and how distressed they are at the time of separation. Instead of focusing on these extinction methods, gentler methods that respect where the child is developmentally should be considered.
I hear people argue all the time that we don't need to be as responsive to our children because there aren't wild animals anymore. We couldn't be looking at the issue any more wrong if we tried.