Insomnia in higher education: Prevalence, validation, and measurement invariance in medical sciences students

Copy igh © 2025 Zanjan Uni e si y o Medical Sciences. Published by Zanjan Uni e si y o Medical Sciences. This wo k is licensed unde a C ea i e Commons A ibu ion-NonComme cial 4.0 In e na ional license (h ps://c ea i ecommons.o g/licenses/by- nc/4.0/). Noncomme cial uses o he wo k a e pe mi ed, p o ided he o iginal wo k is p ope ly ci ed. Insomnia in highe educa ion: P e alence, alida ion, and measu emen in a iance in medical sciences s uden s Zah a Nejad-Eb ahim Soumee1, Ami hossein Rasouli1, Ha e Ti ga i Se aji2, Sima Jahanbakhsh3, Omid Saed4* 1S uden Resea ch Commi ee, Depa men o Clinical Psychology, School o Medicine, Zanjan Uni e si y o Medical Sciences, Zanjan, I an 2Depa men o Psychology, Facul y o Educa ional Sciences and Psychology, Uni e si y o Mohaghegh A dabili, A dabil, I an 3S uden Resea ch Commi ee, School o Medicine, Zanjan Uni e si y o Medical Sciences, Zanjan, I an 4Depa men o Clinical Psychology, School o Medicine, Zanjan Uni e si y o Medical Sciences, Zanjan, I an A icle in o Abs ac In oduc ion Insomnia is a widesp ead heal h issue, as i is one o he mos commonly epo ed heal h complain s and he mos common sleep diso de [1]. Sleeping diso de s a e es ima ed o a ec 15-35% o he gene al public, and app oxima ely 30% o medical s uden s [2]. A comp ehensi e analysis o se en s udies ound ha insomnia a ec s a signi ican po ion o s uden s, wi h p e alence a es anging om 9.4% o 38.2% [3]. Mo eo e , Yassin e al. [4] epo ed an insomnia p e alence o 18.3% among medical s uden s. Insomnia mani es s as a ange o sleep dis u bances, including di icul y in alling asleep, s aying asleep, waking up oo ea ly, o expe iencing unsa is ac o y sleep quali y. Addi ionally, pa ien s diagnosed wi h insomnia mus also epo expe iencing impai men in hei e e yday unc ioning as a ou come o hei sleep di icul ies [5]. Insomnia diso de is usually accompanied by a wide ange o nega i e heal h ou comes and ele a es he likelihood o de eloping di e se psychological issues and challenges, including dep ession and anxie y [6]. Insomnia also signi ican ly impai s academic pe o mance [7]. A c oss-sec ional s udy o a ound Nejad-Eb ahim Soumee e al. J Med Edu De . 2025; 18(1): 32-41 Jou nal o Medical Educa ion De elopmen Backg ound & Objec i e: Insomnia, a widesp ead sleep diso de , impac s 15-35% o he gene al popula ion and a conce ning 30% o medical sciences s uden s. This s udy aims o assesses he psychome ic p ope ies, ac o s uc u e and measu emen in a iance o he Insomnia Se e i y Index (ISI) in I anian medical uni e si y s uden s. Ma e ials & Me hods: This c oss-sec ional s udy included 370 medical uni e si y s uden s (54.9% emales). A e p o iding a de ailed in oduc ion ega ding he pu pose o he s udy and ecei ing pa icipan s' consen online, hey we e eques ed o ill ou he Insomnia Se e i y Index (ISI) and Pi sbu gh Sleep Quali y Index (PSQI). Con i ma o y ac o analysis and hie a chical eg ession analysis we e used o examine he ac o s uc u e and p edic insomnia se e i y. Resul s: The esul s o desc ip i e s a is ics showed ha he p e alence o clinical insomnia was 22.6% in male and 27.9% in emale s uden s, and 62.2% o male and 67.5% o emale s uden s had poo sleep quali y. CFA showed ha he one- ac o model wi h all i ems was he mos sui able s uc u e (x2 = 13.82, d = 9, GFI = 0.990, CFI = .994, TLI = 0.986, RMSEA = 0.038). The s udy's indings indica e ha he ISI exhibi s measu emen in a iance ac oss gende s, ensu ing i s unbiased applica ion o bo h male and emale popula ions. Fu he mo e, his scale demons a ed accep able eliabili y and alidi y. Finally, he esul s o hie a chical eg ession analysis indica ed ha he poo sleep quali y was a signi ican p edic o o insomnia se e i y (β = 0.389). Conclusion: The Pe sian e sion o ISI showed s ong alidi y and eliabili y. These indings indica e ha insomnia se e i y could be measu ed adequa ely in I anian samples using he ISI. Keywo ds: medical s uden s, insomnia diso de , p e alence s udy, psychome ics *Co esponding au ho : Omid Saed, Commi ee, Depa men o Clinical Psychology, School o Medicine, Zanjan Uni e si y o Medical Sciences, Zanjan, I an Email: [email protected] O iginal A icle A icle his o y: Recei ed 15 Jun. 2024 Accep ed 2 Feb. 2025 Published 14 Ap . 2025 How o ci e his a icle: Nejad-Eb ahim Soumee Z, Rasouli A, Ti ga i Se aji H, Jahanbakhsh S, Saed O. Insomnia in highe educa ion: P e alence, alida ion, and measu emen in a iance in medical sciences s uden s. J Med Edu De . 2025; 18(1): 32-41. [ DOI: 10.61186/edcj.18.1.32 ] [ Downloaded om edujou nal.zums.ac.i on 2025-10-03 ] 1 / 10 Nejad-Eb ahim Soumee e al.: Insomnia in highe educa ion: P e alence, alida ion, and measu emen in a iance in medical sciences s uden s Jou nal o Medical Educa ion De elopmen ¦ Volume 18 ¦ Issue 1¦ 2025 33lopmen ¦ Volume 17 ¦ Issue 54¦ 2024 50,000 No wegian s uden s showed ha sleeping less han 5 hou s and mo e han 10 hou s, compa ed o hose sleeping 7 o 9 hou s, is associa ed wi h ailing exams [8]. In gene al, day ime sleepiness, low le els o a en ion, and impai ed memo y/decision-making ha a ise om sleep dep i a ion can p o ide a sui able explana ion o poo academic pe o mance [9]. Hea y academic wo kload, p o essional a i udes and habi s, as well as poo awa eness o sleep hygiene a e among he ac o s ha educe he du a ion and quali y o sleep, in medical s uden s, consequen ly leading o hei poo academic pe o mance [10]. Gi en he consequences o insomnia discussed o s uden s, he exis ence o a ins umen o diagnose and assess his diso de in he s uden popula ion seems necessa y. Al hough polysomnog aphy has eme ged as a c ucial ins umen in he assessmen o many sleep diso de s, i is no he ecommended app oach o diagnosing insomnia [5]. Consequen ly, he diagnosis o insomnia elies p ima ily on he indi idual's sel - epo ed expe iences and symp oms. While s uc u ed and semi-s uc u ed clinical in e iews a e becoming mo e commonly u ilized in clinical se ings, hese me hods a e highly ime- consuming and necessi a e ex ensi e knowledge abou sleep diso de s. As a esul , he e is a need o simple and e icien ins umen s o measu e he se e i y o insomnia in o de o acili a e he diagnos ic p ocess [11]. The Insomnia Se e i y Index (ISI) is a sel -adminis e ed ques ionnai e ha cap u es wo o he mos common insomnia complain s: di icul y alling asleep and equen nigh ime awakenings [12]. The ISI, de eloped in 1993, has eme ged as a aluable ins umen in bo h clinical p ac ice and esea ch s udies, also he ISI demons a es alidi y o use ac oss a b oad age ange, and i has p o en o be a aluable assessmen ins umen o indi iduals wi h di e se condi ions, including man al diso de s [13], and o he clinical p oblems [14]. Psychome ic e alua ions o he ISI ha e been conduc ed o he English [15], F ench [16], Spanish [17], and Chinese [18] e sions, and s udies ha e consis en ly demons a ed he ins umen 's eliabili y and adequa e concu en alidi y wi h o he sleep assessmen measu es. In I an, he psychome ic cha ac e is ics o o he ools in he ield o sleep, including Pi sbu gh Sleep Quali y Index [19] and e ised Adolescen Sleep Hygiene Scale [20], ha e been examined. These ools espec i ely add ess indi iduals' pe cep ions o hei sleep quali y and sleep hygiene beha io s, bu none assess he se e i y o insomnia. The e o e, he ad an age o he ISI is i s di ec measu emen o insomnia se e i y. Howe e , he e is no alida ion o he Pe sian e sion o his ques ionnai e in he popula ion o I anian medical sciences s uden s. Hence, he pu pose o he p esen s udy is o examine he ac o s uc u e, psychome ic p ope ies, and measu emen in a iance o he ISI ques ionnai e in he popula ion o I anian medical sciences s uden s. Ma e ials & Me hods Design and se ing(s) This c oss-sec ional, psychome ic s udy in es iga ed he ISI among Bachelo , Pos g adua e, and PhD s uden s a Zanjan Uni e si y o Medical Sciences, I an. The Resea ch E hics Commi ee o he Zanjan Uni e si y o Medical Sciences app o ed he s udy (App o al ID: IR.ZUMS.REC.1396.35). Pa icipan s and sampling All pa icipan s o his s udy we e I anian and Pe sian- speaking, and we e selec ed using con enience sampling. In a ious s udies, di e en sugges ions ha e been made o de e mining he app op ia e sample size o psychome ic s udies. These sugges ions ange om 5 o 20 pa icipan s pe i em [21]. In he p esen s udy, 50 pa icipan s pe i em we e used. The inclusion c i e ia o his s udy included in o med consen and an age ange o 18 o 50 yea s. The exclusion c i e ion was a desi e o wi hd aw om he s udy o andom esponse o he i ems. Tools/Ins umen s The ollowing ques ionnai es we e used o da a collec ion, (ISI): The ISI is a 7-i em ques ionnai e ha measu es he se e i y o insomnia expe ienced o e he pas wo weeks. I is he mos widely used ins umen in esea ch o assessing insomnia se e i y . Each i em is a ed on a 5-poin Like scale, wi h sco es anging om 0 o 28. Highe sco es indica e g ea e se e i y o sleep dis u bances and associa ed day ime symp oms. The ISI's alidi y and eliabili y ha e been con i med in a ious s udies [22]. The Pi sbu gh Sleep Quali y Index (PSQI): The PSQI is a sel -adminis e ed ques ionnai e, de eloped by Buysse e al. [23], ha assesses sleep quali y o e he pas mon h. The ques ionnai e consis s o 19 ques ions/i ems o ganized in o se en componen s. Each componen is sco ed om 0 o 3, esul ing in a global sco e anging om 0 o 21. A global sco e exceeding 5 indica es poo sleep quali y. The PSQI has been alida ed in a ious coun ies and demons a ed good eliabili y and alidi y in bo h clinical and non- [ DOI: 10.61186/edcj.18.1.32 ] [ Downloaded om edujou nal.zums.ac.i on 2025-10-03 ] 2 / 10 Nejad-Eb ahim Soumee e al. Insomnia in highe educa ion: P e alence, alida ion, and measu emen in a iance in medical sciences s uden s 34 Jou nal o Medical Educa ion De elopmen ¦ Volume 18 ¦ Issue 1 ¦ 2025 clinical samples [24]. In I an, Shadzi e al. examined he eliabili y and alidi y o his ques ionnai e, among medical s uden s and epo ing sa is ac o y psychome ic p ope ies [25]. Da a collec ion me hods To ensu e accu a e ansla ion, he Pe sian e sion o he ISI was p epa ed in acco dance wi h in e na ional guidelines o c oss-cul u al adap a ion o sel - epo measu es [26]. A eam o expe s, including a clinical psychologis and a psychia is , ansla ed he ISI i ems in o Pe sian. Subsequen ly, an English language expe conduc ed a back- ansla ion in o English o ensu e he accu acy and comple e alignmen o he Pe sian and English e sions [27]. Following se e al ounds o e iew and e inemen o add ess any g amma ical o con en - ela ed conce ns, he ansla ed Pe sian e sion o he ISI was inalized and p epa ed o implemen a ion, main aining close alignmen wi h he o iginal English ins umen . Sampling was conduc ed h ough he online pos ing o b ie explana ions o he pu pose o his esea ch, along wi h a pa icipa ion link, on uni e si y social media ne wo ks. Be o e comple ing he scale, pa icipan s we e p o ided wi h in o med i ual consen . Following da a collec ion, he esponses we e sc eened o alidi y. Ou lie s we e iden i ied using Mahalanobis dis ance, and in alid esponses we e lagged. In alid esponses included ixed and con adic o y esponses. Da a analysis The i s s ep in he analysis was o conduc a desc ip i e analysis o he da a o unde s and he dis ibu ion o demog aphic a iables, insomnia se e i y, and sleep quali y in s uden s. his in ol ed equency dis ibu ions and g aphical ep esen a ions we e used o isualize he da a. To in es iga e he ac o s uc u e o he ISI, CFAs we e conduc ed ollowing an explo a o y ac o analysis. Th ee models we e es ed: a single- ac o model wi h 7 i ems, a wo- ac o model wi h 7 i ems, and a h ee- ac o model wi h 7 i ems. Model i was assessed using he ollowing indices: chi-squa e i s a is ics (CMIN/DF), inc emen al i index (IFI), Tucke -Lewis index (TLI), compa a i e i index (CFI), and oo mean squa e e o o app oxima ion (RMSEA, 90% CI). goodness o i was de ined as CMIN/DF ≤ 3, TLI, IFI, and CFI ≥ 0.900, and RMSEA ≤ 0.05 [28]. Measu emen in a iance was employed o assess he deg ee o in a iance be ween gende s ( emales s. males). Measu emen in a iance was assessed o de e mine he ex en o which he ISI exhibi s equi alen psychome ic p ope ies ac oss gende s. This analysis e alua es whe he he cons uc o in usi e hough app aisals is measu ed in he same way o bo h gende s, ensu ing he eliabili y and alidi y o compa isons ac oss g oups. Measu emen in a iance was es ed using a se ies o inc easingly cons ained models including Con igu al, Me ic, and Scala . Model i was compa ed using he change in CFI (ΔCFI) and RMSEA (ΔRMSEA) be ween he less es ic i e and mo e es ic i e models. Cu o alues o accep able in a iance we e ΔRSMEA ≤ 0.015 and ΔCFI ≤ 0.01[29]. To assess he ques ionnai e in e nal consis ency, C onbach's alpha was calcula ed. Fu he mo e, he c i e ion alidi y was assessed by examining i s co ela ions wi h sleep quali y measu e. The da a we e analyzed using SPSS e sion 27 o desc ip i e s a is ics, and AMOS e sion 24 o Con i ma o y Fac o Analysis (CFA). Resul s As shown in Table 1, a o al o 370 s uden s pa icipa ed in he s udy, wi h 45.1% (n = 167) being male and 54.9% (n = 203) being emale. The mean age o he pa icipan s was 23.79 yea s (SD = 4.48), wi h ages anging om 18 o 51 yea s. Mos pa icipan we e single (91.6% o men; 75.4% o women). In e ms o educa ional s a us, 73.1% o men and 29% o women we e pos g adua e s uden s. The p e alence o clinical insomnia was 22.6% in men and 27.9% in women. In addi ion, 37.8% o men and 32.5% o women had good sleep quali y. Table 1. Sociodemog aphic and clinical a iables acco ding o gende Men (n=167) Women (n=203) n % n % Ma i al s a us Single 153 91.6 153 75.4 Ma ied / In ela ionship 14 8.4 50 24.6 Educa ional a ainmen Unde g adua e 45 26.9 144 71 Pos g adua e 122 73.1 59 29 Insomnia se e i y Non-clinical 58 34.8 64 31.6 Sub-clinical 71 42.6 83 40.8 Mild-clinical 37 22 50 24.6 Se e -clinical 1 0.6 6 3 Sleep quali y PSQI sco e < 5 63 37.8 66 32.5 PSQI sco e > 5 104 62.2 137 67.5 Age mean (SD) 24.59 (4.35) 23.13 )4.48) Abb e ia ions: SD, s anda d de ia ion; PSQI, Pi sbu gh sleep quali y index; n and %, sample size and pe cen ages. [ DOI: 10.61186/edcj.18.1.32 ] [ Downloaded om edujou nal.zums.ac.i on 2025-10-03 ] 3 / 10 Nejad-Eb ahim Soumee e al.: Insomnia in highe educa ion: P e alence, alida ion, and measu emen in a iance in medical sciences s uden s Jou nal o Medical Educa ion De elopmen ¦ Volume 18 ¦ Issue 1¦ 2025 35 Table 2 displays he mean, s anda d de ia ion, skewness, ku osis, and C onbach's alpha o he i ems. he dis ibu ion o samples based on he ku osis and skewness o he i ems does no exceed he s anda d ange o +2. The co ec ed i em- o al co ela ion indica es a mode a e and signi ican ela ionship be ween he i ems and he o al sco e. The in e nal consis ency coe icien s based on C onbach's alpha did no exceed 0.80 a e emo ing any o he i ems. Pa icipan s esponded o all ques ionnai e i ems in a nea ly uni o m manne , and he dispe sion was low. CFA was conduc ed using Amos e sion 24. To u he assess and alida e he ac o s uc u es iden i ied in explo a o y ac o analysis, CFA was pe o med. The examina ion o he esul s showed ha he one- ac o model exhibi ed he bes and mos app op ia e i indices. The esul s o he CFAs a e p esen ed in Table 3. As shown in Table 3, he inal ull-i em model, has he ollowing cha ac e is ics x2 = 13.82, d = 9, GFI = 0.990, CFI = 0.994, TLI = 0.986, RMSEA = 0.038. In he inal one- ac o model, he pa h coe icien s o each i em wi h i s unde lying ac o ange om 0.49 o 0.81. This indica es ha each i em has an accep able p edic i e weigh wi h i s main ac o . Table 2 displays he ac o loadings o he i ems. Acco ding o, he ac o loading alues o he i ems we e abo e 0.596, anging om 0.596 in i em 3 o 0.815 in i em 2. Table 3 p esen s he esul s o he measu emen in a iance es ing o he single- ac o model. The model displayed sa is ac o y i indices o bo h males and emales, as indica ed by he TLI, CFI, and RMSEA. Addi ionally, he con igu al, me ic, and scala in a iance models es ed be ween gende g oups showed sa is ac o y i indices based on he TLI, CFI, and RMSEA. Only he con igu al in a iance models exhibi ed minimal deg ada ion in model i (Δx2 = 15.428; p = - 0.042; ΔCFI = - 0.012; ΔTLI = - 0.013; ΔRMSEA = 0.007), as well as be ween he me ic and scala in a iance models (Δx2 = 1.954; p= - 0.001; ΔCFI = - 0.001; ΔTLI = - 0.001; ΔRMSEA = < 0.001). Consequen ly, in a iance was es ablished ac oss bo h gende s. Table 2. I em-Le el s a is ics and ac o s uc u e o he ISI (n = 370) I ems Mean (SD) Skewness Ku osis Co ec ed i em- o al C onbach’s α i dele ed Fac o loading 1a. Di icul y alling asleep 1.16 (1.06) 0.68 - 0.21 0.56 0.79 0.700 1b. Di icul y s aying asleep 1.04 (1.05) 0.88 0.18 0.50 0.80 0.644 1c. P oblem waking up oo ea ly 1.61 (1.26) 0.36 - 0.90 0.48 0.80 0.625 2. Sleep sa is ac ion 1.72 (1.02) 0.26 - 0.44 0.70 0.76 0.815 3. In e e ence 2.09 (1.10) - 0.09 -.72 0.45 0.80 0.596 4. No iceabili y 1.61 (1.09) 0.21 - 0.83 0.54 0.79 0.677 5. Dis ess 1.18 (1.09) 0.62 - 0.49 0.65 0.77 0.770 Eigen alues 3.367 Pe cen age o a iance 48.10 Abb e ia ions: SD, s anda d de ia ion. No e: The loadings indica e he s eng h o he ela ionship be ween each i em and i s espec i e ac o . Eigen alue ep esen s he eigen alue associa ed wi h each ac o . Pe cen age o a iance indica es he p opo ion o a iance explained by each ac o . C onbach's alpha alue ep esen s he eliabili y coe icien . Co ec ed coe icien indica es he C onbach's alpha alue a e he emo al o each i em. skewness and Ku osis measu e he shape o he dis ibu ion. M signi ies he a e age esponse o each i em. SD ep esen s he s anda d de ia ion o esponses. [ DOI: 10.61186/edcj.18.1.32 ] [ Downloaded om edujou nal.zums.ac.i on 2025-10-03 ] 4 / 10 Nejad-Eb ahim Soumee e al. Insomnia in highe educa ion: P e alence, alida ion, and measu emen in a iance in medical sciences s uden s 36 Jou nal o Medical Educa ion De elopmen ¦ Volume 18 ¦ Issue 1 ¦ 2025 Table 3. Fi s a is ics o he con i ma o y ac o analysis model and Measu emen in a iance (n = 370) Model X2 d GFI CFI TLI RMSEA Fac o s uc u e in a iance  Model 1. 1- ac o ull-i em ISI 13.825 9 0.990 0.994 0.986 0.038  Model 2. 2- ac o ull -i em ISI 28.737 11 0.978 0.978 0.957 0.066  Model 3. 3- ac o ull -i em ISI 42.597 9 0.968 0.958 0.901 0.101 Measu emen in a iance χ2 (d ) P CFI TLI RMSEA (90% CI)  Con igu al in a iance 28.383 (18) 0.050 0.987 0.970 0.970 0.040 (0.000; 0.066)  Me ic in a iance 43.811 (24) 0.008 0.975 0.957 0.957 0.047 (0.024; 0.069)  Scala in a iance 45.756 (25) 0.007 0.974 0.956 0.956 0.047 (0.025; 0.069) No e: p < 0.05 indica es signi icance a he 5% le el, and p < 0.01 indica es signi icance a he 1% le el. Abb e ia ions: X², chi-squa e s a is ic; d , deg ees o eedom; GFI, goodness o i index; CFI, compa a i e i index; TLI, Tucke -Lewis index; RMSEA, oo mean squa e e o o app oxima ion; P, p- alue o he chi-squa e es o in a iance; CI, con idence in e al. Con e gen alidi y was assessed using he A e age Va iance Ex ac ed (AVE) index. An AVE alue g ea e han 0.5 is gene ally conside ed accep able. In he p esen s udy, he AVE was es ima ed o be 0.51. In o de o assess C i e ion alidi y o he 7-i em ISI, we analyzed he co ela ion be ween i s o al sco e wi h o he sleep- ela ed scales. The esul s demons a e ha he ela ionship be ween he o al sco e o he ISI wi h Pi sbu gh Sleep Quali y Index, show signi ican co ela ions, anging om weak o mode a e ( = 0.52 p < 0.01). In e nal consis ency and composi e eliabili y we e used o assess he eliabili y o he p esen ques ionnai e. Figu e 1. The inal model Acco ding o he esea ch indings, he Composi e Reliabili y (CR) was calcula ed o be 0.865, and he C onbach's alpha was 0.813. These esul s indica e ha he ques ionnai e has adequa e eliabili y in he I anian popula ion. A hie a chical Mul iple eg ession analysis was conduc ed o examine he con ibu ion o Sleep Quali y in p edic ing sleep- ela ed p oblems (Table 4). In his in es iga ion, he se e i y o insomnia was examined as he esul a iable, wi h demog aphic ac o s and Sleep Quali y se ing as p edic o s. The eg ession analysis was ca ied ou in a wo-s ep p ocess. In he i s s ep age, gende and ma i al we e en e ed in o he model. The esul s indica ed ha none o hem can signi ican ly p edic ed insomnia se e i y. In he second s ep, age, gende , ma i al, and Sleep Quali y we e en e ed in o he model. The esul s showed ha in his s ep, only Sleep Quali y (β = 0.389) signi ican ly p edic ed insomnia se e i y. This sugges s ha o each 0.389 uni ise in PSQI, e ealing o poo sleep quali y, he e is a co esponding one-uni inc ease in he se e i y o insomnia. The R2 alue o he eg ession models in he wo s eps we e 0.006 and 0.395, espec i ely ep esen ing ha he inal model p edic s 38.9% o he insomnia se e i y. [ DOI: 10.61186/edcj.18.1.32 ] [ Downloaded om edujou nal.zums.ac.i on 2025-10-03 ] 5 / 10 Nejad-Eb ahim Soumee e al.: Insomnia in highe educa ion: P e alence, alida ion, and measu emen in a iance in medical sciences s uden s Jou nal o Medical Educa ion De elopmen ¦ Volume 18 ¦ Issue 1¦ 2025 37 Table 4. Hie a chical eg ession model o insomnia se e i y R R2 R2 change B SE β Sig. S ep 1 0.079 0 0.006 0.512 Age 0.035 0.068 0.029 0.513 0.608 Gende 0.698 0.585 0.066 1.193 0.234 Ma i al 0.331 0.807 0.024 0.410 0.682 S ep 2 0.395 0.156 0.150 < 0.001 Age 0.024 0.062 0.020 0.381 0.703 Gende 0.350 0.541 0.033 0.646 0.519 Ma i al 0.569 0.745 0.041 0.763 0.446 Sleep quali y 1.03 0.128 0.389 8.060 < 0.001 Abb e ia ions: R, co ela ion coe icien ; R², coe icien o de e mina ion; R² change, change in R² when a new a iable is added o he model; B, uns anda dized eg ession coe icien ; SE, s anda d e o ; β, s anda dized eg ession coe icien ; , -s a is ic; Sig, Signi icance le el. Discussion The aim o he p esen esea ch was o examine he psychome ic cha ac e is ics, ac o ial s uc u e, and measu emen in a iance o he Insomnia Se e i y Index among I anian medical sciences s uden s. The ISI demons a ed app op ia e in e nal eliabili y and con e gen alidi y. The indings sugges ed ha he single- ac o model p o ed o be he mos sui able model in he s uden sample, aligning wi h p e ious esea ch ou comes. The cu en esea ch demons a es ha clinical insomnia a ec ed 22.6% o male s uden s and 27.9% o emale s uden s. This ou come aligns wi h he indings o he me a-analysis s udy ca ied ou by Zeng e al. [30], which e ealed a highe occu ence o insomnia among emale s uden s as compa ed o male s uden s. The explana ions o he highe p e alence o insomnia in women, especially emale s uden s, seem o be mul i ac o ial [30]. In gene al, women end o be mo e exposed o un a o able socioeconomic condi ions, such as acqui ing lowe income o a aining lowe educa ional le els [31], and he e o e emale s uden s may expe ience mo e s ess ega ding hei u u e and ca ee . Fu he mo e, women a e mo e likely o ace psychia ic p oblems like dep ession and anxie y [32], which se e as isk ac o s o insomnia in women. As a esul , emale s uden s expe ience g ea e emo ional dys unc ion and epo mo e insomnia. Fu he mo e, he esul s showed ha 62.2% o male s uden s and 67.5% o emale s uden s had poo sleep quali y. In gene al, ca eine consump ion, s ess, and i egula sleep-wake pa e ns can dec ease sleep quali y, and men al heal h issues (such as dep ession, psychia ic diso de s, pe cei ed s ess, and anxie y) a e undoub edly de imen al o sleep quali y [33]. Gi en ha s uden s may s ay up la e a nigh and wake up ea ly due o academic demands and social in e ac ions, and end o sleep mo e on holidays, hei sleep-wake pa e ns a e i egula . Addi ionally, due o academic and wo k- ela ed issues, s uden s expe ience high le els o s ess. Fu he mo e, du ing exam pe iods, s uden s may inc ease hei ca eine consump ion o s ay mo e ale and awake. As a [ DOI: 10.61186/edcj.18.1.32 ] [ Downloaded om edujou nal.zums.ac.i on 2025-10-03 ] 6 / 10 Nejad-Eb ahim Soumee e al. Insomnia in highe educa ion: P e alence, alida ion, and measu emen in a iance in medical sciences s uden s 38 Jou nal o Medical Educa ion De elopmen ¦ Volume 18 ¦ Issue 1 ¦ 2025 esul o all hese ac o s, he sleep quali y o s uden s dec eases. Mo eo e , he gende di e ences in sleep quali y p oblems a e mainly a ibu ed o he p io i iza ion o emo ional diso de s and socioeconomic inequali ies [34], which lead o highe le els o expe ienced s ess. The suscep ibili y o women o poo sleep quali y may also s em om gende -based di e ences in sleep biology, which a e exace ba ed by he highe le els o emo ional diso de s in women [35]. The e o e, all o hese ac o s syne gis ically con ibu e o a g ea e educ ion in he sleep quali y o emale s uden s compa ed o male s uden s. The indings indica ed ha he ISI is a eliable ins umen o assessing he se e i y o insomnia in he I anian medical s uden popula ion. Speci ically, he esul s demons a ing he good in e nal consis ency o his scale a e consis en wi h he indings om p e ious esea ch [36]. In his s udy, h ee models we e es ed: one, wo, and h ee- ac o model (wi hou i em dele ion). The esul s o he CFA indica ed ha he one- ac o model was he mos app op ia e model o he I anian medical sciences s uden popula ion, accoun ing o 48.10% o he o al a iance o he ques ionnai e. This inding is consis en wi h he esul s o s udies in Sweden [37], and he Uni ed S a es [36], bu inconsis en wi h o he s udies (11, 38). In explaining his inding, i can be said ha in he p esen s udy, he wo- ac o and h ee- ac o models we e also ai ly sui able, bu he one- ac o model was he bes and mos app op ia e model o explaining he Insomnia Se e i y Index in he I anian medical s uden popula ion. Addi ionally, he linguis ic and cul u al di e ences be ween he I anian popula ion and he popula ions o o he s udies can be men ioned. The measu emen in a iance implies ha he ISI can be u ilized in a su icien ly unbiased manne among bo h male and emale esponden s. Pu nick and Bo ns ein [39] ha e sugges ed ha scala measu emen in a iance analyses se e as dynamic and in o ma i e e alua ions o a cons uc 's unc ioning ac oss g oups, a he han se ing as ga eway es s. These esul s con ibu e o he g owing body o li e a u e on he psychome ic obus ness o he ISI and unde sco e i s c oss-gende applicabili y. Fu he mo e, he esul s indica ed ha he Pe sian e sion o he ISI (ISI-P) had sa is ac o y con e gen alidi y (signi ican posi i e co ela ion) wi h he sleep quali y measu emen ins umen , = 0.52, p < 0.001. This psychome ic p ope y is aligns wi h he indings o p e ious s udies [17]. The esul s o he hie a chical eg ession analysis poin o he p edic i e ole o sleep quali y in he se e i y o insomnia (β = 0.389). This indica es ha sleep quali y accoun s o 38.9% o he a iance in insomnia se e i y. The PSQI, used in ou s udy o measu e sleep quali y, has been widely alida ed and shown o be e ec i e in assessing a ious dimensions o sleep quali y, including subjec i e sleep quali y, sleep du a ion, sleep la ency, sleep dis u bances, habi ual sleep e iciency, and day ime dys unc ion [23]. Poo sco es on hese dimensions we e signi ican ly co ela ed wi h highe ISI sco es, indica ing mo e se e e insomnia. This is align wi h p e ious s udies ha ha e ound a s ong ela ionship be ween sleep quali y, as measu ed by he PSQI, and insomnia se e i y [40]. In examining he b oade implica ions o hese indings, i is essen ial o conside he mul i ace ed na u e o sleep quali y and i s de e minan s. Fac o s such as sleep hygiene, psychological s ess, academic wo kload, and li es yle habi s can signi ican ly in luence sleep quali y. In o he wo ds, p ac ices ha comp omise good sleep hygiene, such as ex ensi e sc een usage be o e bed, inconsis en sleep schedules, and excessi e ca eine in ake, can wo sen sleep quali y and heigh en he isk o de eloping insomnia [41]. Mo eo e , psychological ac o s play a c i ical ole in sleep quali y. The e is a s ong connec ion be ween s ess, anxie y, and dep ession, as well as poo sleep quali y and insomnia. Resea ch has ound ha people wi h highe s ess le els and nega i e a ec a e mo e p one o expe iencing poo sleep quali y and, in u n, de eloping mo e p onounced insomnia [15]. The in e play be ween psychological ac o s and sleep quali y sugges s ha in e en ions aimed a educing s ess and imp o ing men al heal h could be e ec i e in mi iga ing insomnia se e i y. This s udy had a ew limi a ions such as did no con oling o medica ion ea men in he sample da a. Fu u e s udies can add ess his ac o . The con e gen alidi y o he ISI-P scale was assessed using only one measu emen ins umen . The s udy elied on a single sou ce o da a (sel - epo ) o e alua ing insomnia se e i y. Fu u e esea ch could conside inco po a ing addi ional measu es, such as sleep dia ies o objec i e sleep assessmen s, o p o ide a mo e comp ehensi e e alua ion. Despi e hese limi a ions, he indings con ibu e o he g owing body o e idence suppo ing he psychome ic p ope ies o he ISI in he I anian medical s uden popula ion. Conclusion In his s udy, he c oss-cul u al adap a ion o he ISI was igo ously conduc ed in acco dance wi h es ablished [ DOI: 10.61186/edcj.18.1.32 ] [ Downloaded om edujou nal.zums.ac.i on 2025-10-03 ] 7 / 10 Nejad-Eb ahim Soumee e al.: Insomnia in highe educa ion: P e alence, alida ion, and measu emen in a iance in medical sciences s uden s Jou nal o Medical Educa ion De elopmen ¦ Volume 18 ¦ Issue 1¦ 2025 39 guidelines, and i s ac o s uc u e, psychome ic p ope ies and measu emen in a iance we e examined in a sample o I anian medical sciences s uden s. The esul s o his s udy s eng hen he psychome ic alidi y o he ISI and u he ein o ce i s s uc u al alidi y. Addi ionally, he esul s o he eg ession analysis showed ha sleep quali y is he bes p edic o o insomnia se e i y. O e all, he indings o his s udy can acili a e u u e esea ch and clinical in e en ions ela ed o he se e i y o insomnia. Howe e , u he s udies a e needed o deepen ou unde s anding o insomnia se e i y and i s ela ionship wi h o he a iables ha impac indi idual unc ioning. E hical conside a ions The Resea ch E hics Commi ee o he Zanjan Uni e si y o Medical Sciences (ZUMS), in Zanjan, I an app o ed he s udy (App o al ID: IR.ZUMS.REC.1402.176). All pa icipan s ga e w i en in o med consen , and hey could wi hd aw om he s udy a any s age. A i icial in elligence u iliza ion o a icle w i ing The au ho s decla e ha hey did no use gene a i e A i icial In elligence (AI) and AI-assis ed echnologies in he w i ing p ocess o his pape . Acknowledgmen s The au ho s wan o hank all s uden s o Zanjan Uni e si y o Medical Sciences (I an) who ac i ely pa icipa ed in his s udy. Con lic o in e es s a emen The au ho s ha e no con lic s o in e es o decla e Au ho con ibu ions ZNE, AR and OS and designed, conduc ed he s udy, pe o med he s a is ical analyses, and w o e he manusc ip . HTS pa icipa ed in he design and coo dina ion and helped o d a he manusc ip . All au ho s ead and app o ed he inal manusc ip Funding Zanjan Uni e si y o Medical Sciences has inancially suppo ed his s udy. Da a a ailabili y s a emen Da a will be made a ailable on eques . Re e ences 1. Ohayon MM. Epidemiology o insomnia: wha we know and wha we s ill need o lea n. Sleep Medicine Re iews. 2002;6(2):97-111. [h ps://doi.o g/h ps://doi.o g/10.1053/sm .2002.0186]. 2. Ohayon MM, Guilleminaul C. Epidemiology o sleep diso de s. Sleep: a comp ehensi e handbook. 2006;73. [h ps://doi.o g/DOI:10.1002/0471751723]. 3. Ib ahim JM, Abouelezz NF. Rela ionship be ween insomnia and compu e use among s uden s a Ain Shams Uni e si y, Cai o, Egyp . Egyp ian Jou nal o Communi y Medicine. 2011;29(2). [h ps://doi.o g/1110- 1895]. 4. Yassin A, Al Mis a ehi AH, Beni Yonis O, Aleshawi AJ, Momany SM, Khassawneh BY. 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