Many parents can relate to the perpetual exhaustion that comes with raising a newborn.
While mothers and fathers often try to grab sleep whenever they can, scientists from the University of California, LA (UCLA) have warned too little shut eye in the first six months after labour can accelerate ageing in women.
The team analysed the DNA of 33 women, aged 23 to 45, both during their pregnancies and in the first year of their child's life.
Results, published in the journal Sleep Health, suggest those who got by on less than seven hours of shut eye a night at the six-month mark had a "biological age" that was three to seven years older than the mothers who managed to nod off for longer.
Seven hours of sleep is towards the lower end of the NHS' recommended six to nine hours a day. The odd night tossing and turning will not cause any lasting health complications. Persistent insomnia, however, has been linked to heart disease, type 2 diabetes and even a premature death.
This comes after scientists from Flinders University, Adelaide, found enforced working from home amid the pandemic has led to more sleep in babies and less daytime fatigue among parents.
"The early months of postpartum sleep deprivation could have a lasting effect on physical health," said study author Professor Judith Carroll.
"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."
Most of the 33 mothers managed five to nine hours a night, however, more than half got by on less than seven hours, both at six months and one year postpartum.
To assess how the women's sleep related to their biological age, the scientists looked for changes to the mothers' DNA via blood samples.
Our DNA provides the codes for making proteins, which carry out many functions within our body's cells. The scientists specifically focused on whether regions of these codes were "open" or "closed".
"You can think of DNA as a grocery store with lots of basic ingredients to build a meal," said Professor Carroll.
"If there is a spill in one aisle, it may be closed and you can't get an item from that aisle, which might prevent you from making a recipe.
"When access to DNA code is 'closed' then those genes that code for specific proteins cannot be expressed and are therefore turned off."
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Specific sites within DNA naturally turn on or off as we age. This process therefore acts as a sort of clock, allowing scientists to estimate an individual's biological age, according to the UCLA team.
In the study, the women who got less than seven hours of sleep a night also had shorter "telomeres" in their immune cells, which act as protective caps at the end of DNA.
Shorter telomeres have similarly been linked to a higher risk of different cancers, heart disease and a premature death.
"We found that with every hour of additional sleep, the mother's biological age was younger," said Professor Carroll.
"I, and many other sleep scientists, consider sleep health to be just as vital to overall health as diet and exercise."
Co-author Professor Christine Dunkel Schetter has stressed new mothers should not panic if they struggle to get the recommended level of shut eye.
"We don't want the message to be that mothers are permanently damaged by infant care and loss of sleep," she said. "We don't know if these effects are long lasting."
Nevertheless, Professor Carroll recommends new mothers take advantage of opportunities to get more sleep, whether it be via naps while their baby is slumbering, or asking their partner, family or friends for help.
"Taking care of your sleep needs will help you and your baby in the long run," she said.
The scientists have stressed more research is required, with a more diverse group of women. It is unclear whether other aspects of being a new mother influences her biological age or if this process is reversible.
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