Too much light might weaken mus­cles

Honolulu Star-Advertiser - - NEWS -

Ev­ery day, peo­ple are ex­posed to hours of ar­ti­fi­cial light from com­put­ers, of­fice lights, even 24-hour light­ing in hos­pi­tals. Now new re­search in an­i­mals shows that ex­ces­sive ex­po­sure to “light pol­lu­tion” could be worse for you than pre­vi­ously known, tak­ing a toll on mus­cles and bones.

Re­searchers at Lei­den Univer­sity Med­i­cal Cen­ter in the Nether­lands tracked the health of rats ex­posed to six months of con­tin­u­ous light com­pared with a con­trol group of rats liv­ing un­der nor­mal con­di­tions — 12 hours of light, fol­lowed by 12 hours of dark.

Dur­ing the study, re­ported in Cur­rent Bi­ol­ogy, the rats ex­posed to con­tin­u­ous light had less mus­cle strength and showed signs of early-stage os­teo­poro­sis. They also got fat­ter, and some mark­ers of im­mune sys­tem health wors­ened. While ear­lier re­search found ex­ces­sive light ex­po­sure might af­fect cog­ni­tion, the new re­search showed a sur­pris­ing ef­fect on mus­cles and bones.

“Not only did mo­tor per­for­mance go down on tests, but the mus­cles them­selves just at­ro­phied, and mice phys­i­cally be­came weaker af­ter just two months,” said Chris Col­well, a sleep spe­cial­ist at the Univer­sity of Cal­i­for­nia, Los An­ge­les, who was not in­volved with the study.

The good news is the ef­fects of light ex­po­sure ap­pear to be re­versible. When the study rats re­turned to their nat­u­ral light-dark cy­cle, their health re­turned to nor­mal af­ter two weeks.

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