The New Year's Day hangover can be deadly for caregivers who have had a night of heavy drinking and awake to find a lifeless baby in the crib.
More than 2,500 babies a year die from sudden infant death syndrome (SIDS), and now researchers now say there may be an association between those deaths and alcohol.
A University of California study published this month in the journal "Addiction," found a 33 percent spike in SIDS deaths on Jan. 1.
Alcohol consumption is also at an all-time high during the holidays.
The study, conducted by sociologist David Phillips, concluded that alcohol was a risk factor for SIDS, although it is unclear whether alcohol is an independent risk or occurs only in conjunction with other known risks, such as co-sleeping with the baby.
It concludes that alcohol "impairs parental capacity," and therefore can put a child at risk.
Scientists took into account the normal increase in SIDS deaths that are reported during the winter months, probably because of colds and respiratory infections, as well as using coverings in the crib for warmth.
The study looked at 129,090 SIDS cases from 1973 to 2006 and also tracked alcohol-related motor vehicle accidents among the general population. Both were at an all-time high on New Year's Day.
In addition, the study showed another rise in SIDS deaths right after April 20, a day celebrated by pot smokers and after July 4, also a time of heavy alcohol use. Babies of mothers who drink are also twice as likely to die of SIDS, according to the study.
"It's logical that when women are inebriated the attentiveness to the child is going to be reduced and the likelihood of getting a child in the situation where a parent puts them at risk would be there," said Dr. Michael Malloy, a neonatologist at University of Texas Medical Branch.
But he cautioned that the study was "ecologic," or population-based, and therefore does not necessarily show a one-to-one relationship between alcohol use and SIDS deaths.
Still, he said the findings were not "unreasonable," given what doctors understand about SIDS and its association with other behaviors like smoking and alcohol use during pregnancy.
Each year more than 4,500 infants die suddenly of no obvious cause in the United States. About half of these events are due to SIDS, which is the leading cause of death among infants aged 1 to 12 months, according to the Centers for Disease Control and Prevention.
In the last decade, SIDS deaths have decreased more than 50 percent, but they are still disproportionately higher among non-Hispanic Black and American Indian/Alaska Native infants.
Before 1992, when parents were first told to put babies to sleep on their backs or sides, 11,000 babies a year died of SIDS.
This new study suggests there should be more investigation into the connection between alcohol and SIDS deaths, according to Betty McEntire, executive director of the American SIDS Institute, which focuses on research.
"We know there is a link, but not a real close link," she said. "The association between maternal drinking, binge drinking and SIDS probably occurs in pregnancy. We also know that SIDS happens in winter and the cooler months. People use cover more in the winter. Babies with colds also have higher rates of SIDS."
In a typical scenario, parents check in on their sleeping infant to find him or her dead. SIDS leave parents with a guilt and sadness that follows them throughout their lives.
"As a professional researcher, I have known a lot of parents whose babies have died of SIDS," said McEntire. "I don't think there is anything more devastating. You always feel responsible."
The cause of SIDS is unknown, although there are several theories.
Many doctors and researchers now believe that SIDS is not a single condition that is always caused by the same medical problems, but infant death caused by several different factors.
These factors may include problems with sleep arousal or an inability to sense a build-up of carbon dioxide in the blood. Almost all SIDS deaths occur without any warning or symptoms when the infant is thought to be sleeping.
SIDS is most likely to occur between 2 and 4 months of age, and 90 percent occur by 6 months of age, according to the Mayo Clinic.
Babies who are at increased risk are those who sleep on their stomachs, are exposed to cigarette smoke, sleep in the same bed as their parents or have soft crib bedding. Multiple birth and premature babies of those with a brother or sister who died of SIDS are also more vulnerable.
SIDS also affects boys more frequently than girls and can be linked to poverty or lack of prenatal care.
Alcohol use is now implicated because "anything that decreases parents' arousal increases the risk of SIDS," said researcher McEntire. "Don't sleep with the baby and definitely not when using alcohol or other drugs as sedatives.
"We are beginning to piece the puzzle together," she said. "We think most babies who die suddenly and unexpectedly with no known causes had a defect at birth, and [we] even think it's in the neurological system, in the part of the system that affects arousal, temperature control and blood pressure."
She points to the "triple risk model" to explain why some babies are more prone to SIDS: a genetic predisposition, exposure to an external situation [co-sleeping, blanketing] and being at a developmentally vulnerable age, under 1 year.
When babies are placed on their stomachs or if their faces are covered by bedding or if they sleep alongside a parent, they may rebreathe air, increasing carbon dioxide levels.
"Their arousal is not working right and they need to wake up, but they don't," said McEntire. "In and of itself, it's not a cause of death, but since we don't know which babies can safely sleep and which can't, we have to err on the side of safety."
The most important way to reduce risk is to make sure the baby has a "safe place to sleep."
Other big precautions include raising the baby in a smoke-free environment during pregnancy and beyond and putting babies to sleep on their backs with no crib cover, bumper pads or toys -- "nothing but the baby," said McEntire.