AdvancedSleep-PhaseSyndrome(780.55-1)
SynonymsandKeyWords:Phaseadvance,stableasynchronyrelativetotypical environmental patterns, evening somnolence and early morning wakefulness, extremelarkishness.
EssentialFeatures:
Advanced sleep-phase syndrome is a disorder in which the major sleep episode is advanced in relation to the desired clock time, resulting in symptoms of compelling evening sleepiness, an early sleep onset, and an awakeningthatisearlierthandesired.
Advanced sleep-phase syndrome is marked by a patient’s intractable and chronic inability to delay the onset of evening sleep or extend sleep later into the morninghoursbyenforcingmoreconventionalsocialsleepandwaketimes. The major presenting complaint may concern either the inability to stay awake in the evening, orearlymorningawakeninginsomnia, orboth.Unlikeothersleepmaintenance disorders, the early morning awakening occurs after a normal amount of otherwise undisturbed sleep. In pure cases, there is no major mood disturbance during the waking hours. Unlike in other causes of excessive sleepiness, daytime schoolorworkactivitiesarenotaffectedbysomnolence.However,eveningactiv- itiesareroutinelycurtailedbytheneedtoretiremuchearlierthanthesocialnorm. Typicalsleep-onsettimesarebetween6p.m.and8p.m.,andnolaterthan9p.m., andwaketimesarebetween1a.m.and3a.m.,andnolaterthan5a.m. These sleep-onset and wake times occur despite the patient’s best efforts to delay sleep tolaterhours.
AssociatedFeatures:Negativepersonalorsocialconsequencesmayoccurdue to leaving activities in the early to midevening hours in order to go to sleep. Attemptstodelaysleeponsettoatimelaterthanusualmayresultinfallingasleep duringsocialgatherings,ormayhavemoreseriousconsequences,suchasdrowsinessorfallingasleepwhiledrivingintheevening. Afflictedindividualswho attempt to work evening or night shifts would presumably have marked difficulty staying awake during the evening and early morning hours. If patients are chronically forced to stay up later for social or vocational reasons, the early-wakening aspect of the syndrome could lead to chronic sleep deprivation and daytime sleepinessornapping.
Course:Notknown.
PredisposingFactors: Noneknown.
Prevalence:Apparentlyrare.
AgeofOnset:Given the apparent shortening of the endogenous period of the circadiantimingsystemthataccompaniesaging,advancesleep-phasesyndrome istheoreticallymorelikelytooccurinelderlyindividuals.
SexRatio:Notknown.
FamilialPattern:Noneknown.
Pathology:Patientswithadvancedsleep-phasesyndromehaveonlyrarelycome to clinical attention, and no particular anatomic or biochemical pathology has beendescribed.Thedisorderispresumedtobetheconverseofthedelayedsleep- phase syndrome in terms of circadian-system pathophysiology (i.e., a partially deficient phase-delay capability resulting in the symptoms of evening sleepiness andearlymorningawakening).However,almostallnormalhumansstudiedin time-isolation facilities have shown endogenous timing systems with periods of longer than 24 hours, implying that the normal task of synchronizing to the 24- hourdaymayrequireonlyaphase-advancecapability. Thus,alternativeexplanations of advanced sleep-phase syndrome might include an inherently “fast” endogenous circadian timing system or a too-powerful or oversensitive phase- advancecapability.
Complications:SeeAssociatedFeatures.
PolysomnographicFeatures:In order to determine the sleep-wake cycle, polysomnography is best performed over two consecutive nights, with an interveningmultiplesleeplatencytest(MSLT). Thefirstnightisperformedoverthe patient’s habitual sleep period (e.g., 7 p.m.-2 a.m.), as ascertained from a sleep- wakelog. TheMSLTshouldbegintwohoursafterthepatient’stimeofhabitual awakening. (Alternatively, the MSLT can be performed over a period terminating twohoursbeforebedtimeofthesecondnightofrecording.) Thesecondnightof polysomnography should commence at the patient’s desired bedtime and extend tothedesiredtimeofawakening(e.g.,11p.m.-7a.m).
During the first night of recording, the patient’s sleeping hours, sleep onset, sleep latency (less than 20 minutes), sleep staging, and sleep duration are normal forage. TheMSLTdemonstratesnormaldaytimealertness(meansleeplatency greater than 10 minutes), with normal sleep latency on the first nap two hours after spontaneous awakening. (If the MSLT is performed in the alternative mannerasdescribedabove,thesleeplatencyonthelastnapwillbenormalorshort induration.)Thesecondnightofrecordingwilldemonstrateaninitialsleeplatencythatisnormalorshortindurationandaprolongedperiodofwakefulnessatthe endoftherecording,withnormalsleepbeforetheterminalawakening.
OtherLaboratoryTestFeatures: Nonehelpful.
Differential Diagnosis: A mild degree of phase-advanced sleep may be a nor- mal accompaniment of the aging process and may account for the early awakeningpatternofmanyelderlyindividuals.Theearlymorningawakeningofpatients with major affective disorder, which actually occurs in only about one third of such patients, is usually accompanied by other sleep and somatic symptoms and alteredmood.Polysomnographyindepressedpatientsis
typicallyabnormal,with diminished to absent slow-wave sleep, shortened latency to the first REM period, andnumerousawakenings. Theinabilitytosleeplatedifferentiatespatientswith advanced sleep-phase syndrome from those with insufficient nocturnal sleep, in whicheveningsleepinessandnappingarecommon.
DiagnosticCriteria:AdvancedSleep-PhaseSyndrome(780.55-1)
A.Thepatientcomplainsofaninabilitytostayawakeuntilthedesiredbed- timeoraninabilitytoremainasleepuntilthedesiredtimeofawakening.
B.Thereisaphaseadvanceofthemajorsleepepisodeinrelationtothe desiredtimeforsleep.
C.Thesymptomsarepresentforatleastthreemonths.
D. Whennotrequiredtoremainawakeuntilthedesired(later)bedtime, patientswillexhibitthefollowingfindings:
1. Haveahabitualsleepperiodthatisofnormalqualityandduration,with asleeponsetearlierthandesired
2. Awakenspontaneouslyearlierthandesired
3. Maintainstableentrainmenttoa24-hoursleep-wakepattern
D.Polysomnographic monitoring during a 24- to 36-hour period demonstrates anadvanceinthetimingofthehabitualsleepperiod.
E. Thesymptomsdonotmeetthecriteriaforanyotherdisordercausinginabilitytomaintainsleeporexcessivesleepiness.
Note: If the sleep disorder is believed to be socially or environmentally induced, state and code as advanced sleep-phase syndrome (extrinsic type). If there is evidence that the sleep disorder is due to an abnormal circadian pace- maker or its entrainment mechanism, state and code as advanced sleep-phase syndrome(intrinsictype).
MinimalCriteria:AplusCplusE.
SeverityCriteria:
Mild: The patient is habitually unable, over a two-week period, to stay awake untilwithintwohoursofthedesiredsleeptime;thedisorderisusuallyassociatedwithmildinsomniaormildexcessivesleepiness.
Moderate:The patient is habitually unable,over a two-week period,to stay awake until within three hours of the desired sleep time; the disorder is usuallyassociatedwithmoderateinsomniaormoderateexcessivesleepiness.
Severe:Thepatientishabituallyunable, overatwo-weekperiod,tostay awake untilwithinfourhoursofthedesiredsleeptime;thedisorderisusuallyassociatedwithsevereinsomniaorsevereexcessivesleepiness
DurationCriteria:
Acute:6monthsorless.
Subacute:Morethan6monthsbutlessthan1year.
Chronic:1yearorlonger.
Bibliography:
KameiR,HughesL,MilesL,DementW.Advanced-sleep-phasesyndromestudiedinatimeisolation facility.Chronobiologia1979;6:115.
MoldofskyH,MusisiS,PhillipsonEA.Treatmentofacaseofadvancedsleep-phasesyndromebyphase advancechronotherapy.Sleep1986;9:61–65.
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