Study: Shift work chronically impairs cognition

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Long-Term Shift Work Linked To Impaired Brain Func­tion (Forbes):

“Accord­ing to results of a new study, long-term shift work may lead to impaired brain pow­er which could involve cog­ni­tive skills such as think­ing, rea­son­ing and memory…The impact was much greater after a peri­od of 10 or more years of such a work pat­tern — and seen to be much greater for those work­ing a rotat­ing shift pat­tern…

Com­pared with per­sons who had nev­er worked this type of shift, those who had done so for 10 or more years had low­er glob­al cog­ni­tive and mem­o­ry scores — equiv­a­lent to 6.5 years of age relat­ed cog­ni­tive decline…While the effects of the long-term shift work may be reversed, the study sug­gests that recov­ery may take at least five years…

The results of the research sug­gest that it is impor­tant to mon­i­tor the health of peo­ple who have worked rotat­ing shift sched­ules for 10 years in order to eval­u­ate any dete­ri­o­ra­tion in brain function.”

Study: Chron­ic effects of shift work on cog­ni­tion: find­ings from the VISAT lon­gi­tu­di­nal study (Jour­nal of Occu­pa­tion­al Envi­ron­men­tal Med­i­cine). From the abstract:

  • Objec­tives: Shift work, like chron­ic jet lag, is known to dis­rupt work­ers’ nor­mal cir­ca­di­an rhythms and social life, and to be asso­ci­at­ed with increased health prob­lems (eg, ulcers, car­dio­vas­cu­lar dis­ease, meta­bol­ic syn­drome, breast can­cer, repro­duc­tive dif­fi­cul­ties) and with acute effects on safe­ty and pro­duc­tiv­i­ty. How­ev­er, very lit­tle is known about the long-term con­se­quences of shift work on cog­ni­tive abil­i­ties. The aim of this study was to assess the chronic­i­ty and reversibil­i­ty of the effects of shift work on cognition.
  • Meth­ods: We con­duct­ed a prospec­tive cohort study of 3232 employed and retired work­ers (par­tic­i­pa­tion rate: 76%) who were 32, 42, 52 and 62?years old at the time of the first mea­sure­ment (t1, 1996), and who were seen again 5 (t2) and 10 (t3) years lat­er. 1484 of them had shift work expe­ri­ence at base­line (cur­rent or past) and 1635 had not. The main out­come mea­sures were tests of speed and mem­o­ry, assessed at all three mea­sure­ment times.
  • Results: Shift work was asso­ci­at­ed with impaired cog­ni­tion. The asso­ci­a­tion was stronger for expo­sure dura­tions exceed­ing 10?years (dose effect; cog­ni­tive loss equiv­a­lent to 6.5?years of age-relat­ed decline in the cur­rent cohort). The recov­ery of cog­ni­tive func­tion­ing after hav­ing left shift work took at least 5?years (reversibil­i­ty).
  • Con­clu­sions: Shift work chron­i­cal­ly impairs cog­ni­tion, with poten­tial­ly impor­tant safe­ty con­se­quences not only for the indi­vid­u­als con­cerned, but also for society.

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