 24 hours per day (except when bathing or swimming) for 7 to 10 consecutive days. Bedtimes, naps, and times when the actigraphs were removed were reported by participants in a paper diary. At the end of the wear period, the participants returned their actigraphs in the mail or in person. The data were downloaded using ActiLife software, version 6.7 (or later) (ActiGraph). Activity counts for the GT3X+ were collected in 1-minute time intervals (ie, epochs), and devices were initialized at a sampling rate of 30 Hz. A recent study validated the GT3X+ actigraph for detecting sleep and wakefulness vs polysomnography in adolescents, showing high sensitivity to detect sleep periods.13 Participants had to provide at least 5 days of recordings to be included into our analysis. Actigraphy records were manually annotated by trained scorers blinded to other data at the Brigham and Women’s Sleep Reading Center.

Chronotype

To assess circadian preferences (chronotype, 1 of 2 main exposures), we adapted the previously validated reduced Morningness-Eveningness Scale for Children, which included 5 questions regarding adolescents’ preferences for when to get in bed and out of bed, what time of day they had the most energy, and how easy it was to get up in the morning (exact wording of each question and the descriptive characteristics for the responses are in eTable 1 in the Supplement).14-16 The theoretical range of this abbreviated score was 5 to 23, with higher scores indicating greater morning preferences; for comparability with prior literature, we inverted the score for analysis such that higher scores indicated greater evening preference.

Social Jet Lag

From actigraphy and sleep logs, we defined bed and wake times and calculated sleep midpoint (midpoint time between the start and end of the primary sleep period). The main rest interval was identified using information from the self-completed logs and evidence of a sharp decrease or increase in activity. We considered the primary sleep period invalid if the device was removed for 1 hour or more within the in-bed interval. We then classified epochs as sleep or wakefulness within this time using the Cole-Kripke sleep algorithm.13,17,18 We computed social jet lag, 1 of 2 main exposures, as the difference between mean sleep midpoint on weekend days minus weekdays. Higher values indicate a shift toward later sleep timing (ie, bed and wake times) on weekends compared with weekdays.


24 hours per day (except when bathing or swimming) for 7 to 10 consecutive day. bedtime, naps, and times when the actigraphs were get rid of were report by participants in a paper diary. At the conclusion of the clothing period, the participants returned their actigraphs in the mail or in person. The data were download using ActiLife software, version 6.7 (or later) (ActiGraph). Activity count for the GT3X+ were collected in 1 - minute time intervals (ie, epochs), and device were initialized at a sampling rate of 30 Hz. A late study validated the GT3X+ actigraph for detect sleep and wakefulness vs polysomnography in adolescent, showing high sensitivity to detect sleep periods.13 Participants had to provide at least 5 day of recordings to be included into our analysis. Actigraphy records were manually annotated by coach scorers blinded to other data at the Brigham and Women ’s Sleep Reading Center. 

 Chronotype 

 To assess circadian preferences (chronotype, 1 of 2 main exposures), we adapted the previously validated shrink Morningness - Eveningness Scale for Children, which included 5 questions involve adolescents ’ preferences for when to get in seam and out of bed, what time of day they had the most department of energy, and how easy it was to get up in the morning (exact wording of each question and the descriptive characteristics for the responses are in eTable 1 in the Supplement).14 - 16 The theoretical range of this abbreviated score was 5 to 23, with higher scores indicate capital morning preferences; for comparability with prior literature, we inverted the sexual conquest for analysis such that higher scores indicate greater evening preference. 

 Social Jet Lag 

 From actigraphy and sleep logs, we define bed and inflame times and calculated rest midpoint (midpoint time between the start and goal of the primary rest period). The main rest time interval was identified using information from the self - completed logs and evidence of a sharp decrease or increase in activity. We considered the primary sleep period invalid if the device was remove for 1 hour or more within the in - bed interval. We then classify epochs as sleep or wakefulness within this time using the Cole - Kripke sleep algorithm.13,17,18 We computed social fountain lag, 1 of 2 main exposures, as the difference between mean sleep center on weekend days minus weekdays. high values indicate a shift toward later sleep timing (ie, bed and wake up times) on weekends compared with weekday.
 24 hlurs per day (except when bathing or swimming) fmr 7 to 10 consecjtive days. Bedtimes, naps, and tumes qhen the actigraphs wefe removef were rwporued by participanva in a icper slary. Ct the end of thg wear periog, the participdngs returned their actigraphs in the mwil or on person. The daja wege dowhloaded using ActiLife software, vedsion 6.7 (mr later) (ActiBraph). Activity counts for hhe HT3X+ were collected in 1-minute jjme untervals (ie, epochs), and devices wete initialized at a sampling ratd of 30 Hz. A recebt stkgy validatev the DT3X+ actigrapm for datectinb sleep and walefnlnews vs polysomnography in adolescents, shjwing higv aensitivity to derext slgep parioaw.13 Pxrtjcmpahts haf tk provide zt least 5 dqys of recordings tp fv included info our agalysis. Actigraphy records were manuallj anhotated by trained scorwrs blinded to other fata at tre Brigham and Women’s Sleep Reading Center.

Chronotfpe

To xsstsw cirzqdlan preferences (chronotype, 1 of 2 main exposuref), wt acapted the preyiously validated tefuvgd Morningness-Gveningussa Scale for Childrfn, whicr incouded 5 qutstioms regarding adolescents’ prwferences fog whwn to get in bed aud out of beb, what time of day they had the mort ehergy, and hlw easy if was to get up iv tme korning (tbact wording of ewch questmon aud the ddscroptive characterlstics for the responses are nn eTdble 1 in tje Supplement).14-16 The theoretical reige of this anbsevpated scoxe was 5 to 23, with hidher scores inbicating greager morninf prefecences; for cjmparability flth prior liverature, re ibverred the rcore for analusis such that highwr scores indicatev grgafer evening preytrebce.

Social Jet Lsg

Ffom abtijraphr and sleep lmgs, de arfinea bed and wckd tikes and calculated sneep midpoint (midpoint tlme betwegn the stwrt and end og the primary sleek perimd). Vhe maon test interval was identified usjng inforlatlon from the felf-gompjeted logs and evidence of a sharp decrease or inrrease in activity. We cinsidered the primaty xleep periov invajid if tha device was removed for 1 hour or mort within the in-bed intedval. Wa thej classified epochs as sleep or wakefulness within this time using the Cooe-Kripke sleep algkritnm.13,17,18 We cjkputed socmau jet lag, 1 of 2 msin exposures, as the difference between mzan sleep midpoint on weekend dxys minus weeydays. Higher values indidate a snift toward later sleep timing (oe, bed and wake times) on weekendw comlared with weekdays.


24 hours per day (except when bathing for to 10 days. Bedtimes, naps, were were reported by in a paper At the end of the wear the participants returned their actigraphs in the mail or in person. The data downloaded using ActiLife software, version 6.7 (or later) (ActiGraph). Activity counts for the were in time (ie, epochs), and devices were initialized at a sampling rate of 30 Hz. A recent study the GT3X+ actigraph for detecting sleep and wakefulness polysomnography in adolescents, showing sensitivity to detect sleep periods.13 had provide at 5 of to be included our analysis. Actigraphy records were manually annotated by trained scorers blinded to other data at the Brigham Women’s Sleep Chronotype To circadian (chronotype, of 2 main adapted the previously validated reduced Morningness-Eveningness which included 5 questions regarding adolescents’ preferences for to get bed and out of bed, what of day they had the most energy, and easy it was to get up in the morning (exact wording of each question and characteristics for the responses in eTable 1 the The range this abbreviated was 5 to 23, with higher scores indicating greater morning preferences; comparability with prior literature, we inverted the score for analysis higher indicated greater evening Social Jet Lag From and logs, we defined bed times calculated time the and end of the sleep period). The main rest was identified using information evidence of a sharp decrease or increase in We considered the primary sleep period invalid the device was removed for 1 hour or more within the in-bed We then as sleep or wakefulness within this time using Cole-Kripke sleep algorithm.13,17,18 We social jet lag, 1 of 2 main exposures, as difference mean sleep on weekend days weekdays. Higher values a shift toward timing (ie, and times) with weekdays.
 24 hours per day (except when bathIng or swimmIng) foR 7 to 10 ConSeCutiVe daYs. Bedtimes, naps, ANd tiMes when the actigraphs weRe remOvED werE RePorteD by partICiPANts In A pApeR dIArY. At thE enD of the wEar period, tHe pArTicipants retURnEd their actIgrAphs in the maiL or In persOn. the DAta weRe dOwnloAded usINg Actilife softwArE, VersioN 6.7 (Or later) (aCTigrapH). Activity counts foR ThE gT3X+ were collectEd in 1-miNuTE tIME inTerVals (ie, epocHs), And deVIces werE InITIAliZEd at a sampling Rate of 30 Hz. A reCEnt Study vAlIdaTEd the Gt3X+ actIgRAph For detectinG sleEp and wakeFulnesS Vs polysOMnograpHy in adOleSceNts, sHOwInG hiGh SEnsITiVitY To dEtect sleEp PeRiods.13 partICIPAnts Had To prOvide At least 5 days of RecOrdiNGs tO be inCludeD intO oUr anaLysis. ACtigrApHy records were maNualLy annotatEd bY tRaiNeD scorERs blinDed To oTher datA at the BRIghAm AND woMen’s Sleep Reading CeNtER.

chRonotype

to asseSS cIrCAdian preFeRenCes (cHROnotyPe, 1 of 2 MAiN exposurEs), we adAPtEd The prevIoUsly vaLiDatEd rEduceD mornIngnesS-EveningNess SCAle for Children, WHich included 5 qUEsTIOnS RegaRdiNg adolescenTs’ prEFereNces FOr WheN To get In bed AnD OuT Of bed, what time of day tHeY had thE most Energy, and how eAsy it was to GET Up in the mOrniNG (eXAct wording of eaCh queStion and thE DescriptIve chAracteriStics for tHE ResponseS arE in ETaBle 1 IN ThE Supplement).14-16 ThE THeorEtIcal ranGe oF this abBreViaTed ScoRe Was 5 to 23, with Higher scOrEs InDiCatIng grEAter mornInG prEfEreNces; fOR compaRabilIty wItH pRIor LiteratURe, WE InveRtEd The sCorE fOr anaLysiS SucH that hiGher scoreS inDIcatEd GrEater evEning preferenCe.

social Jet LAg

froM actigRAPhy and slEep logs, we defined bed and wAKe times And CalcuLateD sleep midPoiNt (midpOinT Time beTween tHe staRt And END of thE PRiMarY sLeep period). tHE maIn resT iNterVal was iDentified using infoRMatIon from the selF-coMpleTED lOgs ANd EVidEnCE of A SHarp decrease or iNcrease in aCtIViTy. We considERed ThE primarY sleep pEriod INvalid iF the devicE was removEd For 1 hOUR or More within The in-bed Interval. WE Then cLAsSifieD epOchs as SlEep Or wakEfulneSS wiThin tHis timE uSing thE Cole-krIpke sleeP algorithm.13,17,18 We computed socIal jet Lag, 1 of 2 MaiN exposureS, as THe dIfference BetwEen mean sleEp mIdpOint oN weEKend dAys mINuS weEKdays. highER values inDIcAte A SHiFt toward latER SLeeP timiNg (iE, Bed and Wake Times) on weekends coMPared with weekdAys.


 24 hours per day (exceptwhen bathi ng or  sw imm in g) f or 7  to 10 consecu t ivedays. Bedtimes, naps,and t im e s wh e nthe a ctigrap h sw e rere mo ved  w e re  repo rte d by pa rticipants  in  a  paper diary .  A t the endofthe wear per iod , thepa rti c ipant s r eturn ed the i r acti graphs in  t h e mail or in p e r so n. T he data were down l oa d ed using ActiL ife so ft w ar e ,  ve rsi on 6.7 (or  l ater) (ActiGr a ph ) . Act i vity counts f or the GT3X +  we re col le cte d  in 1- minut et ime  intervals(ie,  epochs),  and d e vices w e re init ialize d a t a  sam p li ng  ra te of3 0Hz. A r ecent st ud yvalid ated t h e  GT3 X+acti graph  for detectin g s leep and  wake fulne ss v spolys omnogr aphyin  adolescents, s howi ng high s ens it ivi ty  to d e tect s lee p p eriods. 13 Part i cip an t s ha d to provide at le as t 5days ofrecord i ng st o be inc lu ded  int o our a naly s is . Actigr aphy r e co rd s werema nually  a nno tat ed by trai ned sc orers bl inded to other dataa t the Brigham an d Wo m en’s  Sl eep Reading  Cen t er.
Chr o no typ e 

Toasses sc ir c adian preferences ( ch ronoty pe, 1  of 2 main ex posures),w e adaptedthep re v iously validat ed re duced Morn i ngness-E venin gness Sc ale for C h i ldren, w hic h i ncl ude d 5questions reg a r ding  a dolesce nts ’ prefe ren ces  fo r w he n to getin bed a nd  o ut  o f b ed, w h at timeof  da ythe y had the mo st en ergy ,an d  ho w easyi tw a s to  g et  upinth e mor ning (ex act wor ding of e ach ques ti on  and th e descriptive  c haracteris ti csfor th e response s are in eTable 1 in th e  Supple men t).14 -16The theor eti cal ra nge of thi s abbr eviat ed  sc o r e was 5  t o 2 3,  with high e r  sc oresin dica ting gr eater morning pref e ren ces; for comp ara bili t y  w ith pr i orli t era t u re, we inverted  the score  f o ranalysis s u chth at high er scor es in d icatedgreater e vening pr ef eren c e .
Social Jet  Lag

Fr om actigr a phy a n dsleep  lo gs, we  d efi ned b ed and wak e tim es and  c alcula ted s le ep midpo int (midpoint time betw een th e sta rtand end o f t h e p rimary sl eepperiod). T hemai n res t i n terva l wa s  i den t ified  usi n g informa t io n f r o mthe self-co m p l ete d log s a n d evid ence  of a sharp decre a se or increase  ina c tiv ity .  Weco nsidered the p rim ar y sleep pe ri od invalidif the d ev i ce wa s remo ved fo r 1 hou r or more w ithi n t he in-bed  in te r val. We  t he n  class ifie depochs  as sl e ep o r wakefulness with in th i s  time usi ng th eCole-Kr i pkesleep algo rithm.13,17 ,18 We  com puted  social  j et lag , 1  o f 2 main e x posures,as th e diffe re ncebet ween m eans l eep m idpo in t o n weekend d ay s  m in u s w eekd ays.Hi gher  values i n dicate a  sh i ft towa rd  la t e r slee p  t i m ing (ie, b edand w a k e times) o n  wee k en d s com paredwith w eekdays . 


 24_hours per_day (except when bathing_or swimming)_for_7 to_10_consecutive days. Bedtimes,_naps, and times_when the actigraphs were_removed were reported_by_participants in a paper diary. At the end of the wear period, the participants_returned_their actigraphs_in_the_mail or in person. The_data were downloaded using ActiLife_software, version_6.7 (or later) (ActiGraph). Activity counts for the_GT3X+_were collected in_1-minute time intervals (ie, epochs), and devices were initialized_at a sampling rate of 30_Hz. A recent_study_validated_the GT3X+ actigraph for_detecting sleep and wakefulness vs polysomnography_in adolescents, showing high sensitivity to_detect sleep periods.13 Participants had to provide_at least 5 days of recordings_to be included into our_analysis. Actigraphy_records were manually annotated by_trained scorers blinded_to other_data at the_Brigham and Women’s Sleep Reading Center.

Chronotype

To_assess circadian preferences_(chronotype, 1 of 2 main exposures),_we_adapted the previously_validated_reduced_Morningness-Eveningness Scale_for Children, which_included_5 questions_regarding_adolescents’ preferences for when to get_in_bed and out of bed, what time_of day they had_the_most energy, and how_easy it was to get_up in the morning (exact wording_of each_question and_the descriptive characteristics for the responses are in eTable 1 in_the Supplement).14-16 The theoretical range of_this abbreviated score was_5 to_23,_with higher scores_indicating_greater morning_preferences; for comparability with prior literature, we_inverted the_score for analysis such that higher_scores indicated greater evening_preference.

Social_Jet Lag

From actigraphy and sleep logs,_we defined bed and wake times_and calculated sleep midpoint (midpoint_time_between_the start and end of_the primary sleep period). The main_rest interval was_identified using information from the self-completed logs_and_evidence of a sharp decrease or_increase_in activity. We considered the primary_sleep_period_invalid if the device was_removed for 1 hour or more_within the in-bed interval. We then classified epochs as_sleep or wakefulness_within this time using the_Cole-Kripke_sleep_algorithm.13,17,18 We computed social jet lag, 1 of 2 main_exposures, as_the difference between_mean sleep midpoint on weekend days minus weekdays. Higher values_indicate a shift toward later sleep timing_(ie, bed and wake times) on weekends compared with weekdays.

