There's nothing like that new baby smell. No parent will ever forget the sweet, subtle scent of the top of their baby's head. When my son was young I would breathe it in for hours as he laid on my chest or napped, strapped to me in his carrier.
Sniffing the top of his little head made me feel so connected to him, and research suggests that the sweet smell is part of the connection. In fact, a study published decades found that 90% of moms can identify their baby by smell alone. And babies respond to mom's scent, too.
There is a very real connection there and, as reported by the Smithsonian Magazine, when researchers asked groups of women (moms and non-moms) to smell baby pajamas, the dopamine pathways in the adults' brains lit up, and the reaction was stronger for the women who were parents.
For mamas, that baby smell causes a surge of dopamine. This reaction is a reward response, something smilier to what happens when you get the food you've been craving or even a drug you've been craving. The same way a surge of dopamine cause by using drugs encourages people to engage in drug seeking behavior, the surge of dopamine cause by sniffing our babies encourages us to stay close to them.
"These results show that the odor of newborns undoubtedly plays a role in the development of motivational and emotional responses between mother and child by eliciting maternal care functions such as breastfeeding and protection," said Johannes Frasnelli, a postdoctoral researcher at University of Montreal's Department of Psychology, where this study took place.
"The mother-child bond that is part of the feeling of maternal love is a product of evolution through natural selection in an environment where such a bond is essential for the newborn's survival," Frasnelli explained.
In an evolutionary sense, that amazing baby smell helps keep babies alive, and in a physiological sense, it can even help mothers relax.
According to Swedish-language research magazine forskning.se, researchers in the Department of Clinical Neuroscience at Karolinska Institutet in Stockholm are investigating whether or not that smell could one day be used to treat depression.
The team had 30 women smell little hats previously worn by newborn babies. As the women inhaled the scent the researchers studies their brains with a magnetic camera, Sciencenordic reports. Images were also gathered as the women experienced other smells.
The results were compelling: The smell of the baby hats seemed to affect the women's brains similarly to drugs used to treat mental illness.
The researchers have now been given funding to try the experiment with men, but they're pretty sure the results will be the same regardless of the sniffer's gender.
The Swedish scientists don't know exactly why our brains love that baby smell so much, and note that the body odor of newborns contains about 150 different chemicals, so they're still trying to pin down which chemicals are causing the reaction.
The research is still years away, but the team hopes that a one day, a nasal spray capturing that sweet baby head smell may be developed and used to treat mental illnesses, including depression.
[A version of this post was originally published February 16, 2018. It has been updated.]