maintained close to baseline levels following true prophylactic naps while .... of work on the night shift was slightly slower, the energy expenditure was about 10 ...
won( & sriEss.
19 ,vol.
4. No- 3.261-271
Dcaling with shift work: physical fitness, temperature, and napping M, H. BONNET Long Bc2ch vA Hosptil ,nd Unive6n, oaCrliaorn,a,
kvhe, Cilifomu q)822, USA
Thtr prp.r revEvs the efiecb ofsene!.lly coniioll2ble fr.ro6 ruch,s phyiiol .onditionina, lmbl.nt irmpcrrture,.nd amount oapnor neep in:dtusmcnt tonight wort periods:nd shifr work. Onc.rn
.yp..t , 5 l0% dc.lin. r crp.city ao. wo.k in nodum.l wort penods .ompre.l to &ytime work ^ I consistent n.ep wrke p.irods. Thn deftcrscd .rp2.ry wouu dnsiplte il sorke. mintrired routnr. aorS-,6dayr:lterhoving to rn.wshlat Prov.n nerns aor rcceleraling thn adiprrtion,rc .utrcntly not rvrJrbl.. The rbility ro F.rform wor* .lso declin6 ar rhe l.ngth oath. work period
in.r.:5e5 but depending opon individual osls. Physicl condirioning improves mood rnd gcnrrel veu-bcing. but no nrong .vidnce cuftendy indic.t.s lhrt condirioni.g increases tolennce or idrunment to shift work.
In.rcrsedrnrbrenttenpe.rtureincreasesthe$re$ofwoik,rlthoughrtudicrdonorrd.lr.$he2ttri r &dor n, rdJun ntnt to shiti eork Vhile lower nocturnal i.np€rature would be ssumed to redu.c ,.trt nrc$ dnrins n,ght shiii\, supporins d:rr does nor .xnt. Studies h2v. not trddftr\rd th. n€grnve .onrqucn.Ls oa.old nre$ or oa robting alom night to dry shifts with dded hen arc$ Th. proper uscoashort neep p.riod! ctrher rs pr.plr,tion forora5 a rcspont to Ihrat.huge can
."n.liortrre$nccll..Eoash'ltlohtion D.o indiclte thlt p.rfo'nrncc on g.aveyard Jhia6.trnb. n,rintrin.d.lo5e to b.kline trvcls loud{ing EU.prdphyhcric n:p5 vnile peraorman.. m:y de.line by up ro:!)1', wh.n ch nrPl rrc not hkcn while ih€re n cvidence thrt nips o!.ven r.r peri.ds rvthout necp rre 6.neu.,1l in imploving nood in nomrt young rdults, thesc drt, do not rpply to ?.phccmcna nrps. Studier oainrerjc.tcd nipi inply th,t srch nrpsdo Edu.e sleep debt but do not nnply ihr su.h n,ps rrc more ben.icial ihrn longe! de.p pciiods. Nips rppcir to b. no{ .llvtrnnglou' whdr the tr(u,ulrted deep dcbi r ler$. Ktrtr\nt\:
Pn y sn
rl rohtlitionin{ Sh{t Mth; Rotdtirr lhijts; A,ljurm?nt; Wntk bdn;Tnp1annz;
^"np
1. I.rodlction
Thn ptrper derls wth thc cffccls of gcncrally contolhble frctos such as physi.al .o.di
!mbicnt tcmper.ture, rnd aftount ofprior !leeprs vuirblcs in adju$mentto and work lorddcmand. temperrture.rnd nrPl rvill bc .cvicwcd. hd implicrions rnd furre rdorch dncctlons w11l bc dncu$cd Th.rc rrc rel ivcly tiw nud,cs ofcnvno.n,cntal facio. rn shift work, ahholgh ,t r prcbibte th noue, tcmpcrtrrurc. humidity, lrgh!, vibrtrtion. rnd other vruble5 nuy nr.nct n.omplcr l-!\hrons to influence p.rformancc. Ve.y lcw applied nudies hrvc 1ook.d I.ombi.trtions ofvrrirbles, despite thc ihportincc oasuch *udic!, be.rule olrhe ntr6 involvcd The hck ofsuch informlion lregtrently ftekes condusions dirficnk becros. o c Qnnot t.ll if thcsc scvcrtrl componens rre indepcndent. additiv., ,ubtiadivc, or irulnpll.lnyc (Harco.k r.d P,(cc 1985, Rutcnfrr.z and Knruth 1985). rion ing.
nnt rvork. R.s.!rchd.rling with physi.alfttne$
2.
Physical fitnes and
*oikload dcmand
Wh,lc mmy {udics hrlc cgmin.d the trbilny ro perform rvork dn !rrious ti\Li. oa
non{sk rarirblL\. n,duding rimc ol dry
oa work, lcngih of
tr
numb.r
sork piiod, phyricil
londnion of worke6, end number of&ys o. weeks on shifi. havc frcqu.ndy not becn nrcinrrcd.In tict, thererre very few st,dies rhar have conkolled and/or maniPulated these rurbls. This review will look at each of thcse clements independentlv rnd rttenpt to
trnfg rhcm togerhc. where posiblc.
) 1 I tut ,l ,lry oJ watk ln r..c.( ycrB, rn .xplosion in circtrdBn rhythm r.torch har result.d in inc"&J kro$lc.tgL of cir.rdun rhylhms in most b,ological fuf,ctions ind particul.rlv nr nnonc/ordo.rinc .xc.cdon (lhulyrnd Schcvins 1987) A.crusc Phv'.rl wo.k dcn.ods rh. !,n)dudron olen.rgy, chtr!gcs in the relationshiP ol. d,.c rnd respnelo'v v nbl'sin d,ltrn dion Nnh mclJbolic v!.iablc5 dictatcs rhc rbilny ro Pcrform work. Sevcr.l excellcnt ho
,d fi.]d $udies do.umcnr th.se physiologicalchrnges as a function oftime dry (Wolt.zrk-Jaro5zowr 1977, Bu.ger.r. di. 1957, (lein er di. 1968).
llb.rrt(nv
lnrpo int.n..diin rhythn,s for
the Ptoduciion
oiwork
ol
include svmPathetic activnv
glucootico,ds,.re.holamines, a.d pituitary ho.mones Becruse rctivitv in allofthese syt.ms is typrcrlly rcduccd ai night, the av.ilability ofglycogen rrd liPid storcs fo' work durhg thc night rte probably dec.e!$d. Thn should limn theabilityto Perfo.m lonS bouts oair.nuous excr.ne * thet !ime. At night, there is r decrease in.esPnaiorv frequencv .oupl.d snh a rcduclion in ddal volume, viulcaP.ciry and alvcoh. ve,rilation. Cardiac rccompany the noctumelresPiratorychrngcj include decreased rnernlsynolic prc\surc. puls. pre$ure, and usually, hcait.lte (WoJtoik-Jaroszowr 1977, Btr.g.r .r dl
.hrnssrhit 1957.
Klcin
d,l.
Phyn.rliltncs
1968).
and
wo.k crpiciry arc tyPically measured bv I/o:max, which n bscd
on rhe rchtionship betwecn he$trrte and oxygen upoke during inq€sins levch ofwo'k' Ho\L.v.r. lornrultr. dcvelopcd for thc calcuhnon of rO,max hav. been-bxs.d on thc r$uhiofdrytime studics (wojt.zrk Jaroszow. 1977) and rutry not bc dnccdv comPtrrrble to nuntr.r ofnight work, whcrc heart nte, for clamPle st.rts rt 3 low.r lcvcl rnd rnocrd mav ippear mor. npidly.In fac!, bectusc hctrt ntest,ts at a lowcr lcv€lat.i8hr,
'ubjecB
bc morc ht, cspecirlly for vfy shot work Pcoods. unlc$ I/Ozmax s dctelmined .lirc(ly. wojtak-J oeowa (1977) .xamhcd ,/Or nrx. n .pendcndv dctcrmined Jnd .rltulrcd m tr group of2.l subjcc6 (Mtrng ai cithcr 0100 or 0900. Eightv-thrc€ p* ccnt of
t.
n,bj..6hrdilo$.rdcterm,ncdI'o,daxetnisht(l'6L/minvs38timinP
