Lullabies work just as well for soothing a baby to sleep if it is in their native language or a completely foreign dialect, a new study claims.
In trials, Harvard University researchers found infants relaxed when played lullabies that were unfamiliar and in a foreign language, including French and Gaelic.
They found that regardless of if it was Frère Jacques or Twinkle, Twinkle, Little Star, the infant responded in the same way.
Academics saw universal drops in heart rate and higher electrodermal activity – a measure of excitement based on the skin's electrical resistance.
The study suggests the melody carried by the lyric is what babies enjoy, not familiarity with the words themselves.
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Researchers at Harvard's Music Lab have determined that American infants relaxed when played lullabies that were unfamiliar and in a foreign language. Pictured, baby Theo demonstrates the method for measuring physiological responses to lullabies
The finding supports the idea that there is an 'evolutionary function' of music rather than it just being a byproduct of language.
'There's a longstanding debate about how music affects listeners as a result of both prior experiences with music and the basic design of our psychology,' said Samuel Mehr at Harvard's Music Lab.
'Common sense tells us that infants find the lullabies they hear relaxing – is this just because they've experienced their parents' singing before and know it means they're safe and secure or is there also something universal about lullabies that produces these effects, independently of experience?'
To measure the infants' relaxation responses to the recordings, the researchers focused on pupil dilation (pictured) and heart rate changes, among other factors
British babies are being exposed to more than three million microplastic particles every day - produced when bottles are sterilised and formula is prepared.
Researchers from Trinity College Dublin found that bottles with polypropylene release these plastics when exposed to extreme heat, such as from boiling water.
The team tested ten types of baby bottles by following World Health Organisation (WHO) guidelines for preparing formula and sterilising bottles.
Globally, infants are exposed to an average of 1.6 million microplastic particles every day during the first year of their life from polypropylene-based bottles.
In the UK this soars to more than three million per day by six months of age.
The exact impact of these tiny pieces of microplastic - that are up to 100 times smaller than a full stop printed in a book - on the human body are unknown.
The study was conducted at Harvard's Music Lab, which focuses on the psychology of music from infancy to adulthood.
In the experiment, each infant watched an animated video of two characters singing either a lullaby or a non-lullaby.
The songs were chosen through a previous Music Lab study in which adults rated how likely a foreign unfamiliar song was to be a lullaby.
The selection included a total of 16 lullabies and other songs originally produced to express love, heal the sick or encourage dancing.
Languages like Scottish Gaelic, Hopi, and Western Nahuatl, and regions including Polynesia, Central America, and the Middle East were