Scientists have found a link between 'feel good' brain chemical serotonin and cot death.
Researchers have shown that the chemical, which is more usually associated with keeping mood on an even keel, is key to breathing and regulation of body temperature.
Both of these are thought to go awry in cot death, which affects around 300 British babies a year, with boys, premature and low birth weight infants and babies whose parents smoke being at greater risk.
The US researchers used genetic techniques to create mice with an "off switch" on the brain cells, or neurons, that normally make serotonin.
Switching off serotonin production left the animals unable to keep their body temperature up when the air around them was chilled. Lack of serotonin also affected breathing.
When normal mice were exposed to carbon dioxide - which may accumulate when a bay is sleeping face down - they took fast, deep breaths to get the toxic gas out of their systems.
But breathing hardly changed in the animals lacking serotonin, leaving the animals at risk of carbon dioxide poisoning.
"This finding shows that the breathing response to carbon dioxide is regulated by serotonin neurons," the Daily Mail quoted Researcher Susan Dymecki, of the respected Harvard University, as saying.
She said that the finding could help shed light on the causes of cot death, or sudden infant death syndrome, as well as conditions like depression.
"By selectively and abruptly switching off serotonin-producing cells, we can get a definite idea of what body functions the serotonin cells specifically control.
"These findings and the new tools in neuroscience that they bring to the table will help us understand the role of serotonergic [serotonin-producing] neurons in many disorders," added Dymecki. (ANI)
The study has been published in the journal Science.