Psychological detachment from work during non-work time: linear or curvilinear relations with mental health and work engagement?

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1 282 Industrial Halth 2016, 54, Original Articl A SHIMAZU t al. Psychological dtachmnt from work during non-work tim: linar or curvilinar rlations with mntal halth and work ngagmnt? Akihito SHIMAZU 1, 2 *, Ko MATSUDAIRA 3, 4, Jan DE JONGE 2, 5, Naoya TOSAKA 1, Kazuhiro WATANABE 1, 6 and Masaya TAKAHASHI 7 1 Dpartmnt of Mntal Halth, Th Univrsity of Tokyo, Graduat School of Mdicin, Japan 2 Asia Pacific Cntr for Work Halth and Safty, Univrsity of South Australia, Adlaid, Australia 3 Dpartmnt of Mdical Rsarch and Managmnt for Musculoskltal Pain, 22nd Cntury Mdical and Rsarch Cntr, Faculty of Mdicin, Th Univrsity of Tokyo, Japan 4 Clinical Rsarch Cntr for Occupational Musculoskltal Disordrs, Kanto Rosai Hospital, Japan 5 Human Prformanc Managmnt Group, Dpartmnt of Industrial Enginring and Innovation Scincs, Eindhovn Univrsity of Tchnology, Eindhovn, Th Nthrlands 6 Japan Socity for th Promotion of Scinc, Japan 7 National Institut of Occupational Safty and Halth, Japan Rcivd May 19, 2015 and accptd January 12, 2016 Publishd onlin in J-STAGE January 30, 2016 Abstract: This study xamind whthr a highr lvl of psychological dtachmnt during non-work tim is associatd with bttr mploy mntal halth (Hypothsis 1), and xamind whthr psychological dtachmnt has a curvilinar rlation (invrtd U-shapd pattrn) with work ngagmnt (Hypothsis 2). A larg cross-sctional Intrnt survy was conductd among rgistrd monitors of an Intrnt survy company in Japan. Th qustionnair includd scals for psychological dtachmnt, mploy mntal halth, and work ngagmnt as wll as for job charactristics and dmographic variabls as potntial confoundrs. Th hypothsizd modl was tstd with modratd structural quation modling tchniqus among 2,234 rspondnts working in th trtiary industris with rgular mploymnt. Rsults showd that psychological dtachmnt had curvilinar rlations with mntal halth as wll as with work ngagmnt. Mntal halth improvd whn psychological dtachmnt incrasd from a low to highr lvls but did not bnfit any furthr from xtrmly high lvls of psychological dtachmnt. Work ngagmnt showd th highst lvl at an intrmdiat lvl of dtachmnt (invrtd U-shapd pattrn). Although high psychological dtachmnt may nhanc mploy mntal halth, modrat lvls of psychological dtachmnt ar most bnficial for his or hr work ngagmnt. Ky words: Psychological dtachmnt, Mntal halth, Structural quation modling, Work ngagmnt, Curvilinarity Introduction In rcnt yars, scholars hav argud that not only on- *To whom corrspondnc should b addrssd. ashimazu@m.u-tokyo.ac.jp 2016 National Institut of Occupational Safty and Halth job xprincs (how mploys spnd thir working tim) but also off-job xprincs (how thy spnd thir privat or lisur tim) ar crucial for undrstanding mploy wll-bing 1). Mor spcifically, bttr knowldg of off-job rcovry from th dmands xprincd during working tim is imprativ 2). Rcovry can b dfind as a procss during which individual functional systms that hav bn Industrial Halth 2016, 54,

2 PSYCHOLOGICAL DETACHMENT, HEALTH, AND WORK ENGAGEMENT 283 calld upon during a strssful xprinc rturn to thir initial, pr-strssor lvl 3). Rcovry can b rgardd a procss opposit to th strain procss, during which th dtrimntal ffcts of strssful situations ar allviatd or liminatd. Rcovry is also rgardd as an xplanatory mchanism in th rlation btwn acut strss ractions and chronic halth impairmnt 4). Crtain xprincs outsid of work can hlp in allviating ractions to work dmands 5 7). Ths so-calld rcovry xprincs consist of psychological dtachmnt, rlaxation, mastry, and control 8). Psychological dtachmnt; i.., th ability of individuals to mntally switch off from work by not doing work-rlatd tasks and not thinking about work during non-work tim, is considrd th most crucial rcovry xprinc for protcting on s wll-bing rgarding job-rlatd rcovry 2, 9). In th contxt of rspits from work, dtachmnt has bn dscribd as an individual s sns of bing away from th work situation 10). Psychological dtachmnt has bn furthr charactrizd as not bing involvd in workrlatd activitis, such as phon calls, -mails, or othr work-rlatd tasks, during off-work tim 8). Psychological dtachmnt from work xtnds byond th pur physical absnc from th workplac during off-job tim and abstaining from job-rlatd tasks. It implis laving th workplac bhind onslf in psychological trms 11). Th rlation btwn psychological dtachmnt and wll-bing can b xplaind by COR thory 12) and th Effort-Rcovry Modl 3). Consrvation Of Rsourcs (COR) thory assrts that an individual aspirs to prsrv, protct, and build rsourcs. Rsourcs ar charactrizd as objcts, conditions, prsonal charactristics, or nrgis that hav spcific importanc for th individual. According to COR thory, strss occurs whn individuals ar thratnd with rsourc loss, actually los rsourcs, or fail to gain rsourcs following rsourc invstmnt. Th inability to rplnish nrgy rsourcs may lad to longtrm fatigu, which hamprs normal functioning in many aspcts in daily lif, including work. Thus, to rcovr from strss, individuals hav to gain nw rsourcs and rstor thratnd or lost rsourcs. Psychological dtachmnt can contribut to gaining nw rsourcs and rstor thratnd or lost rsourcs. Th Effort-Rcovry Modl 3) holds that ffort xpnditur at work lads to load ractions such as fatigu or physiological activation. Load ractions can accumulat and lad to impaird halth and wll-bing, unlss individuals can rcovr from work. By no longr bing xposd to jobrlatd dmands, load ractions can rturn to pr-strssor lvls, and rcovry can occur bfor th nxt working priod starts. This implis that rcovry stratgis such as psychological dtachmnt during off-work tim can b an opportunity to rturn to and stabiliz at a baslin lvl. Thus, both th Effort-Rcovry Modl and COR thory suggst two complmntary procsss by which rcovry occurs. First, it is important to rfrain from work dmands and to avoid activitis that call upon th sam functional systms or intrnal rsourcs as thos rquird at work. Scond, gaining nw intrnal rsourcs such as nrgy, slf-fficacy or positiv mood will additionally hlp to rstor thratnd rsourcs 8). Prvious studis that xamind th rlation btwn psychological dtachmnt and wll-bing hav rvald that psychological dtachmnt is positivly associatd with mntal halth and ngativly associatd with job strss and burnout 6, 8, 11, 13, 14). Thrfor, w xpct that a highr lvl of psychological dtachmnt during non-work tim will b associatd with bttr mntal halth (Hypothsis 1). Rgarding positiv aspcts of mploy wll-bing, th prsnt study focuss on work ngagmnt, which rfrs to a positiv, fulfilling, work-rlatd stat of mind that is charactrizd by vigor, ddication, and absorption 15). Prvious studis hav shown that psychological dtachmnt is positivly associatd with work ngagmnt 16 18), bcaus dtachmnt may contribut to th prvntion of continud rsourc drain and rstoration of rsourcs 18). If mploys do not unwind from on s work, dpltd rsourcs can lad to low work ngagmnt. Thus, w can assum that low lvls of psychological dtachmnt ar associatd with low work ngagmnt. Howvr, th rlation btwn psychological dtachmnt and work ngagmnt appars to b mor complx. For instanc, Shimazu t al. 19) showd a ngativ rlation btwn ths variabls, suggsting that switching off mntally during off-job tim did not improv work ngagmnt, but rathr dcrasd it. Whn individuals ar highly dtachd from thir jobs during off-job tim, thy may fl difficulty in switching on again in th nxt morning 14), and thy may nd mor tim to mobiliz thir nrgy for thir job, which rsults in impaird work ngagmnt. Ths findings suggst that (vry) low and (vry) high lvls of psychological dtachmnt will b dtrimntal to work ngagmnt. As a rsult, modrat lvls of psychological dtachmnt will b associatd with th highst lvls of work ngagmnt. All ths findings imply non-linar rathr than linar rlations btwn dtachmnt and work ngagmnt, which is in lin with Warr s (1994) assumptions on work 20), mntal halth and wll-bing. Accordingly, w xpct that psychological dtachmnt will

3 284 A SHIMAZU t al. hav a curvilinar rlation (invrtd U-shapd pattrn) with work ngagmnt (Hypothsis 2). Mthod Study population An Intrnt rsarch company with 1.5 million rgistrd rsarch voluntrs agd yars, was usd to conduct a larg Intrnt-basd cross-sctional survy on occupation, halth and wll-bing in W randomly slctd 106,250 voluntrs from 201,170 monitors, living in thr gratr mtropolitan aras of Japan (23 wards of Tokyo, th City of Osaka, and th City of Nagoya). On March 25, 2011, th slctd voluntrs wr invitd to tak part in th study via an -mail containing a link to th survy. Participants rcivd onlin shopping points as an incntiv for participation. In ordr to prvnt doubl rgistration, -mail addrsss wr chckd and a link to th qustionnair was disabld onc th survy was compltd. On March 31, 2011, th survy was closd whn mor than fiv thousand participants rspondd (a total of 5,860 survys wr collctd). Thrfor, a spcific rspons rat could not b calculatd for this survy. Our rspondnts wr vry clos to th popl living in 23 wards of Tokyo, th City of Osaka, and th City of Nagoya in trms of man ag (45.2 yars in our rspondnts, 43.9 in Tokyo, 44.8 yars in Osaka, and 43.8 yars in Nagoya), gndr (50.8% in our rspondnts, 50.7% in Tokyo, 51.5% in Osaka, and 50.7% in Nagoya), and mploymnt status (46.5% rgular mploymnt in our rspondnts, 46.1% in Tokyo, 46.2% in Osaka, and 50.1% in Nagoya). Howvr, our rspondnts had highr ducational lvl (40.9% undrgraduat or highr) than thos living in Tokyo (33.2%), in Osaka (20.8%), and in Nagoya (26.0%) 21, 22). In our rspondnts, th proportion of rspondnts working within primary industris (.g., agricultur, forstry, and fishris) and scondary industris (.g., mining, manufacturing, and constructions) was xtrmly low (0.1% and 7.6% rspctivly). Thrfor, w analyzd rsponss only from thos individuals working in trtiary industris (.g., transport and postal activity, wholsal and rtail trad, accommodations, ating and drinking srvics, financ and insuranc, advrtising, ducation and larning support, and mdical, halth car and wlfar). Individuals with a rportd ag of ithr <20 yars or 65 yars, thos with non-rgular mploymnt, or shift workrs wr xcludd 23 25). A total of 2,234 participants wr rtaind and includd in th analysis. Th man ag of th participants was 41.7 yars (SD=11.3). Of th participants, 63.9% wr mal, 54.4% wr marrid, 55.9% had a univrsity dgr or highr, and 12.2% workd mor than 60 hours pr wk. Masurs Psychological dtachmnt Psychological dtachmnt was assssd using th corrsponding subscal of th Japans vrsion of th Rcovry Exprinc Qustionnair 8, 19), consisting of four itms (i.., I forgt about work, I don t think about work at all, I distanc myslf from my work, and I gt a brak from th dmands of work ). All itms wr scord on a fiv-point Likrt scal, ranging from 1 (do not agr at all) to 5 (fully agr). Rsponss for th 4 itms wr summd to gt a scal scor. Cronbach s alpha cofficint was.86. Mntal halth Mntal halth was assssd using th corrsponding subscal of th SF-36 vrsion ), consisting of fiv itms (i.., Hav you bn a vry nrvous prson?, Hav you flt so down in th dumps that nothing could chr you up?, Hav you flt calm and pacful? (rvrsd), Hav you flt downhartd and blu?, and Hav you bn a happy prson? (rvrsd) ). All itms wr scord on a six-point Likrt scal, ranging from 1 (all of th tim) to 6 (non of th tim). W usd th SF-36 mntal halth summary scor as a masur of mntal halth (Rang: 0 100) 29). Cronbach s alpha cofficint was.84. Work ngagmnt Work ngagmnt was assssd using th short form of th Utrcht Work Engagmnt Scal (UWES) 15), which has bn validatd in Japan 30). Th UWES includs thr subscals that rflct th undrlying dimnsions of ngagmnt: Vigor (3 itms;.g., At my job, I fl strong and vigorous ), Ddication (3 itms;.g., I am nthusiastic about my job ), and Absorption (3 itms;.g., I am immrsd in my work ). All itms ar scord on a svn-point Likrt scal ranging from 0 (nvr) to 6 (always). Rsponss for th 3 itms ach wr summd to gt a scal scor. Cronbach s alpha cofficints wr.87 for vigor,.84 for ddication, and.86 for absorption. Potntial confoundrs W controlld for two typs of potntial confoundrs; i.., (1) job charactristics and (2) dmographic charactristics. Thir rlation with dtachmnt and our outcom masurs is wll-stablishd in th litratur 4, 9, 11). Job charactristics wr assssd using thr scals of Industrial Halth 2016, 54,

4 PSYCHOLOGICAL DETACHMENT, HEALTH, AND WORK ENGAGEMENT 285 th Brif Job Strss Qustionnair (BJSQ 31) ): job dmands, job control and workplac support. Th first two scals consistd of 3 itms ach, for instanc My job rquirs working hard and I hav influnc ovr th pac of my work. Workplac support consistd of 6 itms: 3 itms for suprvisor support and 3 itms for coworkr support. To rciv a mor parsimonious modl and to avoid multi-collinarity, w combind th two subscals in ovrall workplac support du to a high bivariat corrlation (r=0.59; p <.001). All itms wr scord on a four-point Likrt scal, ranging from 1 (disagr) to 4 (agr). Cronbach s alpha cofficints wr.81 for job dmands,.85 for job control, and.86 for workplac support. Dmographic charactristics such as ag, gndr, marriag, ducation, and working hours pr wk wr also includd as potntial confoundrs in th qustionnair. Data analyss To tst th hypothss, w conductd modratd structural quation modling (MSEM) analyss, using th AMOS softwar packag 32). W prfrrd MSEM to hirarchical rgrssion analyss, bcaus MSEM allows multivariat tsting of outcoms, allows assssing and corrcting for masurmnt rror, and provids masurs of fit of th modls undr study. W followd th procdur proposd by Mathiu t al. 33) as dscribd by Cortina t al. 34). Linar psychological dtachmnt and mntal halth had only on indicator that was th standardizd (cntrd) scal scor of th rspctiv factor 33). Th indicator of th latnt curvilinar psychological dtachmnt was th squard trm of th standardizd (cntrd) scal scor of psychological dtachmnt. Work ngagmnt had thr indicators (i.., vigor, ddication, and absorption). Corrlation btwn linar psychological dtachmnt and curvilinar on was constraind to b zro, whras mntal halth and work ngagmnt wr allowd to corrlat. Th paths from th latnt xognous factors to thir indicators wr fixd using th squar roots of th scal rliabilitis, and th rror variancs of ach indicator wr st qual to th product of thir variancs and 1 minus thir rliabilitis. S Fig. 1 for our hypothsizd modl. For mor dtails rgarding th calculation of th rliability scor of th curvilinar trm, Mntal halth Dtachmnt Dtachmnt Mntal Halth Cross-product trm Dtachmnt X Dtachmnt Work Engagmnt Vigor Ddication Absorption Fig. 1. Hypothsizd modl (Modl 1). Not: =rror.

5 286 A SHIMAZU t al. w rfr to Cortina t al. 34). Th fit of th modls was assssd with th chi-squar statistic, th goodnss-of-fit indx (GFI), th comparativ fit indx (CFI), th non-normd fit indx (NNFI), and th root-man-squar rror of approximation (RMSEA). It is suggstd that GFI, CFI, and NNFI valus that xcd.90 and RMSEA valus as high as.08 ar indicativ of accptabl fit 35). Ethics statmnt This study was approvd by th mdical/thics rviw board of th Japan Labour Halth and Wlfar Organization and Th Univrsity of Tokyo mdical dpartmnt. Rsults Simpl statistics Zro-ordr corrlation cofficints ar shown in Tabl 1. Psychological dtachmnt was positivly corrlatd with mntal halth (r =.22, p<.001), and ngativly corrlatd with vigor (r=.04, p<.05), ddication (r =.06, p<.01), and absorption (r =.14, p <.001). Rsults of MSES analyss Rsults of th MSEM-analyss showd that th hypothsizd modl (Modl 1) fits to th data (χ 2 (8)=236.72, p<.001, GFI=.97, NNFI=.93, CFI=.96) although RMSEA valu xcdd.08 (RMSEA=.11). In lin with Hypothsis 1, linar psychological dtachmnt was positivly rlatd to mntal halth (β=.24, p<.001). As to Hypothsis 2, both linar and curvilinar psychological dtachmnt wr ngativly rlatd to work ngagmnt (β=.10, p<.001 and β=.06, p<.01, rspctivly). To nsur that no curvilinar rlation xistd btwn psychological dtachmnt and mntal halth in addition to linar on, w xamind th altrnativ modl that adds th path from curvilinar psychological dtachmnt to mntal halth. Th modl fit of th altrnativ modl (Modl 2: χ 2 (7)=216.11, p<.001, GFI=.97, NNFI=.92, CFI=.97, RMSEA=.12) was similar to on of th hypothsizd modl. Howvr, th chi-squar diffrnc tst, comparing th hypothsizd modl (Modl 1) with th altrnativ modl (Modl 2), shows a significant improvmnt in modl fit ( χ 2 (1)=20.61, p<.001). This mans that th altrnativ modl (Modl 2), including th path from curvilinar psychological dtachmnt to mntal halth, offrs a bttr account of th data than th hypothsizd modl (Modl 1). Thrfor, w dcidd to adopt th altrnativ modl (Modl 2) in furthr xamination. Tabl 1. Dscriptiv statistics for th ky study variabls (N=2,234) Variabl Rang Man SD Ag Gndr a *** 3 Marriag b ***.31*** 4 Education c ***.19***.03 5 Working hours (pr wk) d **.15***.04*.03 6 Job dmands ***.07**.02.09***.26*** 7 Job control ***.02.10***.00.06**.16*** 8 Workplac support * *** 9 Psychological dtachmnt **.07**.05*.11***.25***.07***.05* 10 Mntal halth ***.04*.12***.03.09***.22***.25***.35***.22*** 11 Vigor ***.03.11*** ***.30***.04*.31*** 12 Ddication ***.05*.09***.01.05*.13***.29***.30***.06**.25***.82*** 13 Absorption ***.00.08***.03.06**.14***.27***.24***.14***.18***.79***.83*** Not: *p<.05 **p<.01 ***p <.001. SD: Standard Dviation. a Gndr was codd as 1 (mn) and 0 (womn). b Marriag was codd as 1 (ys) and 0 (no). c Education was codd as 1 (univrsity or highr) and 0 (collg or lowr). d Working hours pr wk was codd as 1 (60=<) and 0 (<60). Industrial Halth 2016, 54,

6 PSYCHOLOGICAL DETACHMENT, HEALTH, AND WORK ENGAGEMENT 287 Mntal halth 1.00 *** Dtachmnt.93 *** Dtachmnt.22 *** Mntal Halth (R 2 =.06) -.10 ***.30 *** -.11 *** Cross-product trm 1.00 *** Dtachmnt X Dtachmnt -.09 **.89 *** Work Engagmnt (R 2 =.02).93 ***.89 *** Vigor Ddication Absorption Fig. 2. Standardizd solution (Maximum Liklihood stimats) of th final (altrnativ) modl (Modl 2: N=2,234). Not: =rror. ***p <.001, **p<.01, *p<.05. As can b sn in Fig. 2, linar psychological dtachmnt was significantly and positivly rlatd to mntal halth (β =.22, p<.001) whras curvilinar psychological dtachmnt was also significantly but ngativly rlatd to it (β=.10, p<.001). In addition, both linar and curvilinar psychological dtachmnt wr significantly and ngativly rlatd to work ngagmnt (β =.11, p<.001 and β=.09, p<.01, rspctivly). Plas not that th rsults rgarding th curvilinar rlationship btwn psychological dtachmnt and work ngagmnt wr similar in all thr sub dimnsions of th construct (i.., vigor, ddication, and absorption). Rgarding th curvilinar rlation btwn psychological dtachmnt and mntal halth, Fig. 3 shows that initially thr is a positiv rlation: mor dtachmnt is associatd with bttr mntal halth. Howvr, at high lvls of psychological dtachmnt, th positiv rlation btwn psychological dtachmnt and mntal halth bcam lss prominnt, and vn sms to disappar. Mntal halth did not incras furthr and rmaind at a high lvl. Fig. 3. Curv-fitting btwn psychological dtachmnt and mntal halth. With rgard to th curvilinar rlation btwn psychological dtachmnt and work ngagmnt, Fig. 4 shows that modrat lvls of psychological dtachmnt wr associatd with th highst lvls of work ngagmnt, whras

7 288 A SHIMAZU t al. Fig. 4. Curv-fitting btwn psychological dtachmnt and work ngagmnt. vry low and vry high dtachmnt wr associatd with lowr lvls of work ngagmnt (i.., invrtd U-shapd pattrn). In a final stp, w conductd additional analysis to control for potntial confoundrs (i.., ag, gndr, marriag, ducation, working hours, job dmands, job control, and workplac support). Spcifically, ach control variabl was includd in th altrnativ modl (Modl 2) as a manifst variabl simultanously and was allowd to rlat to all variabls in th modl. Aftr controlling for confounding variabls, th path cofficints wr virtually th sam as thos of th altrnativ modl (Modl 2), but th modl fit dcrasd (χ 2 (35)= , p<.001, GFI=.91, NNFI=.53, CFI=.82, RMSEA=.14). Ths rsults indicat that th addd rlations of th control variabls to th modl variabls wr wak. Importantly, many control variabls did not significantly affct th structural paths in th modl (i.., 18 out of 48 paths wr not statistically significant). Thrfor, th control variabls wr rmovd from th final modl in Fig. 2. Discussion Th aim of this larg cross-sctional Intrnt survy study was to xamin whthr highr lvls of psychological dtachmnt during non-work tim would b associatd with improvd mploy mntal halth (Hypothsis 1). W also xamind whthr psychological dtachmnt would hav a curvilinar rlation (i.., invrtd U-shapd pattrn) with work ngagmnt (Hypothsis 2). Examination of th curvilinar rlation was novl, bcaus prior rsarch on th function of psychological dtachmnt on work ngagmnt is inconsistnt in this rspct 16 19). As far as th rlation btwn psychological dtachmnt and mntal halth is concrnd, MSEM rvald that not only linar psychological dtachmnt (β=.22, p<.001) but also curvilinar dtachmnt (β=.10, p<.001) was significantly rlatd to mntal halth. This rsult was contrary to our xpctation. Examining Fig. 3, th positiv rlation btwn psychological dtachmnt and mntal halth flattnd aftr highr lvls of psychological dtachmnt. This pattrn of findings suggsts that mntal halth initially improvs whn popl psychologically dtach. Howvr, mploy mntal halth dos not bnfit any furthr from xtrmly high lvls of psychological dtachmnt. It is important to not that mntal halth dos not suffr at such vry high lvls of psychological dtachmnt. Although most prvious studis showd that highr lvls of psychological dtachmnt during non-work tim wr associatd with bttr mploy mntal halth 6, 8, 11, 13), our rsult suggsts that th favorabl ffct of psychological dtachmnt may hav an uppr limit on mntal halth, at last among our participants. Futur rsarch nds to xamin undr which conditions and for whom psychological dtachmnt has such a curvilinar rlation with mntal halth. As to th rlation btwn psychological dtachmnt and work ngagmnt, w also found a curvilinar rlation. Modrat lvls of psychological dtachmnt wr associatd with highst lvls of work ngagmnt, whras vry low and vry high psychological dtachmnt was associatd with lowr lvls of work ngagmnt (i.., invrtd U-shapd pattrn). Vry low lvls of psychological dtachmnt may drain on s rsourcs and inhibit rsourc rstoration, whras vry high lvls of psychological dtachmnt may rquir a longr tim to gt back into working mod in th nxt morning 9). Ths may ngativly impact work ngagmnt, particularly at high lvls of dtachmnt. Finally, it is worth noting that th curvilinar rlation btwn psychological dtachmnt and work ngagmnt rsmbls (albit at a wakr lvl) a prviously found rlation btwn psychological dtachmnt and job prformanc in arlir rsarch 14). Givn that both of ths ar mor strictly work-rlatd variabls, th currnt finding may hav implications for futur rsarch on th topic. Limitations and suggstions for futur rsarch Nxt to svral strngths such as a larg sampl siz and sufficint study powr, thr ar also svral limitations of this study. First, w usd slf-rport survy data. Slfrport masurs may b biasd du to, for xampl, ngativ affct. Common mthod varianc might hav affctd th rsults, suggsting that th tru associations btwn Industrial Halth 2016, 54,

8 PSYCHOLOGICAL DETACHMENT, HEALTH, AND WORK ENGAGEMENT 289 variabls might b wakr than thos obsrvd in this study. Although svral studis hav shown that ths influncs ar not as high as could b xpctd 36 38), our findings should b rplicatd using mor objctiv masurs (.g., pr-ratings of mntal halth and work ngagmnt) in th futur. Scond, w usd a cross-sctional study dsign, which prcluds making causal infrncs. For instanc, our data showd that psychological dtachmnt was rlatd to bttr mntal halth. This might indicat that mor psychological dtachmnt lads to bttr mntal halth. It might also b that individuals njoying bttr mntal halth ar mor likly to dtach thmslvs from thir work. Basd on th cross-sctional analyss of th currnt study, it can only b concludd that psychological dtachmnt is rlatd to mntal halth and wll-bing. Mor longitudinal rsarch is ndd to uncovr th causal squnc in th rlation btwn psychological dtachmnt and its consquncs. Howvr, it should b notd that thr is a growing body of litratur that dmonstrats longitudinal ffcts of psychological dtachmnt on halth and wll-bing, particularly at day-lvl 39 42). Thy support our causal infrncs from both thortical and mpirical viwpoints. Third, our data wr collctd from popl living in thr gratr mtropolitan aras of Japan (23 wards of Tokyo, th City of Osaka, and th City of Nagoya), which rquirs caution rgarding th gnralizability of our findings. Our sampl may not rprsnt othr working populations quit wll. Thrfor, furthr studis ar ncssary to xamin whthr our rsults ar applicabl to workrs in local aras. Fourth, our data wr collctd via th Intrnt, which again rquirs caution rgarding th gnralizability of our findings. It has bn claimd that th socioconomic and ducational status of th avrag Intrnt usr is usually gratr than that of th gnral population 43). Indd, our participants rportd highr ducational status than thos complting nationwid papr-and-pncil survys in Japan 44) and thos living in Tokyo, in Osaka, and in Nagoya 21, 22). Thus, similar to typical Intrnt studis, slfslction might b a limitation of th prsnt study. Finally, psychological dtachmnt did not hav much xplanation for outcoms in our participants. Spcifically, linar and curvilinar psychological dtachmnt xplaind succssivly 6% and 2% of th variancs of mntal halth and work ngagmnt in Modl 2. On possibl xplanation is that w did not xamin th combind ffcts of psychological dtachmnt and othr typs of rcovry xprincs. Until now, only bivariat associations of rcovry xprincs with outcom variabls hav mainly bn invstigatd. Howvr, in rality, it is lss likly that popl us ithr typ of rcovry xprinc xclusivly. Rathr, thy may us various typs of rcovry xprincs simultanously givn th positiv corrlations among thm (.g., r= by Sonnntag 8), and r = by Shimazu t al. 19) ). Hnc, it is important to xamin th combind as wll as indpndnt associations of ach typ of rcovry xprinc with wll-bing in mploys. According to COR thory 12), mploys using various typ of rcovry xprincs simultanously ar assumd to xprinc bttr wll-bing bcaus multipl rcovry xprincs may provid mor opportunity for rcovry from rsourc loss and for rsourc gain. Anothr possibl xplanation is that w did not considr conditions undr which mploys us psychological dtachmnt. This suggsts th possibility that psychological dtachmnt may not b favorabl for vrybody and in all situations 45). For instanc, mploys who xprinc thir jobs as highly maningful and njoyabl might find dtachmnt difficult to achiv, but lack of dtachmnt might b lss of a problm for such popl. Thus, job faturs might modrat th rlation btwn psychological dtachmnt and wll-bing. Futur rsarch nds to xamin th conditions undr which psychological dtachmnt can hav mor favorabl ffcts. Implications for practic Our findings hav som implications for practic. A first implication is that psychological dtachmnt during nonwork tim is associatd with mploy mntal halth and work ngagmnt in diffrnt ways. With rgard to mploy mntal halth, highr lvls of dtachmnt would facilitat bttr mntal halth (although th favorabl ffct of dtachmnt had limitations). It is important that both organizations and suprvisors should support mploy dtachmnt by advising that mploys b as unavailabl as possibl (.g., via -mail, txting or phon) during thir non-work tim. It might b bnficial for workrs to dtach from work if thy do not us thir smartphons or tablts for work-rlatd issus during fr tim 46 48). Howvr, it might also b possibl that chcking on s work -mails hlps to dtach from work in particular circumstancs. For xampl, if s/h is unsur whthr s/h has forgottn to inform a collagu about an important work-rlatd issu, to chck th snt box of his/hr -mail account might hlp him/hr thraftr to dtach from work. Furthr rsarch nds to xamin whthr th us of communication dvics such as smartphons or tablts during non-work tim can b bnficial or not for on s dtachmnt from work. Organizations and suprvisors can also support

9 290 A SHIMAZU t al. mploy dtachmnt by not initiating work-rlatd communication with thir mploys during non-work tim, thrby allowing dtachmnt to occur 14). Suprvisors can act as rol modls in this rspct by not bing availabl during non-work tim. This is particularly important in a country lik Japan, bcaus thos who ar in charg of changing long working cultur in Japan ar oftn work addicts thmslvs 49). Furthrmor, improving working conditions to achiv adquat lvls of job dmands (.g., rduc tim prssur) can b a promising avnu to facilitat psychological dtachmnt bcaus high job dmands can inhibit psychological dtachmnt during off-work tim 2). It is also important for mploys who ar at risk for workaholism (i.., working xcssivly with an obsssiv mannr 50) ) to modify this tndncy, sinc it inhibits psychological dtachmnt 2). Training programs that focus on tim managmnt and problm solving skills might b hlpful, bcaus workaholic mploys tak on mor work than thy can handl and accpt nw tasks bfor complting prvious ons 51). Rational motiv thrapy 52) might b also hlpful, sinc workaholic popl suffr from th blif that thy should b prfct 53). With rgard to work ngagmnt, th rlation with psychological dtachmnt is mor complx and suggst a diffrnt practical implication: Modrat lvls of psychological dtachmnt would b associatd with th highst lvls of work ngagmnt. Although oprationalizing th optimal lvl of psychological dtachmnt sms to b not vry asy, it should b notd that thinking about work may not b ncssarily ngativ pr s 9, 54). Positivly rflcting about on s work (.g., thinking about a rcnt succss or about an inspiring goal) might vn improv work ngagmnt, but this thinking should not b too much thr sms to b an uppr limit for work rflction. Futur rsarch nds to clarify th prfrabl typ and amount of work-rlatd thoughts during off-job tim to improv work ngagmnt. Conclusion Although highr lvls of psychological dtachmnt may nhanc mploy mntal halth, it sms that modrat lvls of psychological dtachmnt ar most bnficial for his or hr work ngagmnt. In futur, mor rsarch is ndd to addrss how, and undr which conditions, to attain optimal lvls of psychological dtachmnt to achiv both bttr mploy mntal halth and gratr work ngagmnt. Rfrncs 1) Shimazu A, Schaufli WB (2009) Is workaholism good or bad for mploy wll-bing? Th distinctivnss of workaholism and work ngagmnt among Japans mploys. Ind Halth 47, ) Shimazu A, d Jong J, Kubota K, Kawakami N (2014) Psychological dtachmnt from work during off-job tim: prdictiv rol of work and non-work factors in Japans mploys. Ind Halth 52, ) Mijman TF, Muldr G (1998) Psychological aspcts of workload. In: Handbook of work and organizational psychology: Vol. 2. Work Psychology, Drnth PJD, Thirry H, d Wolff CJ (Eds.), 5 33, Psychology Prss, Hov. 4) Gurts SAE, Sonnntag S (2006) Rcovry as an xplanatory mchanism in th rlation btwn acut strss ractions and chronic halth impairmnt. Scand J Work Environ Halth 32, ) Edn D (2001) Vacations and othr rspits: studying strss on and off th job. In: Intrnational rviw of industrial and organizational psychology, Coopr CL, Robrtson IT (Eds.), , Wily, Chichstr. 6) Fritz C, Sonnntag S (2005) Rcovry, halth, and job prformanc: ffcts of wknd xprincs. J Occup Halth Psychol 10, ) Sonnntag S (2001) Work, rcovry activitis, and individual wll-bing: a diary study. J Occup Halth Psychol 6, ) Sonnntag S, Fritz C (2007) Th Rcovry Exprinc Qustionnair: dvlopmnt and validation of a masur for assssing rcupration and unwinding from work. J Occup Halth Psychol 12, ) D Jong J, Spoor E, Sonnntag S, Dormann C, Van dn Toorn M (2012) Tak a brak?! Off-job rcovry, job dmands, and job rsourcs as prdictors of halth, activ larning, and crativity. Eur J Work Organ Psychol 21, ) Etzion D, Edn D, Lapidot Y (1998) Rlif from job strssors and burnout: rsrv srvic as a rspit. J Appl Psychol 83, ) Sonnntag S, Bayr UV (2005) Switching off mntally: prdictors and consquncs of psychological dtachmnt from work during off-job tim. J Occup Halth Psychol 10, ) Hobfoll SE (1989) Consrvation of rsourcs. A nw attmpt at concptualizing strss. Am Psychol 44, ) Fritz C, Sonnntag S (2006) Rcovry, wll-bing, and prformanc-rlatd outcoms: th rol of workload and vacation xprincs. J Appl Psychol 91, ) Fritz C, Yanklvich M, Zarubin A, Bargr P (2010) Happy, halthy, and productiv: th rol of dtachmnt from work during nonwork tim. J Appl Psychol 95, ) Schaufli WB, Salanova M, Gonzalz-Romá V, Bakkr AB (2002) Th masurmnt of ngagmnt and burnout: a two sampl confirmatory factor analytic approach. J Happinss Industrial Halth 2016, 54,

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