New mothers may age more due to sleepless nights in the first six months after birth, researchers have reported.
UCLA scientists found too little sleep in the first half-year of a new child's life can add up to seven years to a woman's "biological age", which can differ from chronological age.
A greater biological age can come with a greater risk of disease and earlier death.
DNA analysis found the biological age of mothers who slept less than seven hours a night at the six-month mark were three to seven years older than those who slept for longer than seven hours.
Mothers who slept less also had shorter telomeres in their white blood cells, an issue linked to a higher risk of cancers, cardiovascular diseases, and early death.
"The early months of postpartum sleep deprivation could have a lasting effect on physical health," said the study's first author Judith Carroll, from the UCLA's George F. Solomon Professor of Psychobiology. "We know from a large body of research that sleeping less than seven hours a night is detrimental to health and increases the risk of age-related diseases."
With every hour of additional sleep, the mother's biological age was younger.
"I, and many other sleep scientists, consider sleep health to be just as vital to overall health as diet and exercise," Caroll added, urging mothers to nap when their baby is asleep, or asking for help from family and friends. "Taking care of your sleep needs will help you and your baby in the long run."
With only a small sample size of 33 mothers during the first year of their babies' lives, the authors said more research would be required to replicate the findings, and to look for other contributing factors - as well as to examine if the effects are permanent or reversible.
The study was published in the journal Sleep Health.