Mitler, M.M., Carskadon,
M.A. and Hirshkowitz, M.
Evaluating sleepiness, In
Kryger, M.H., Roth, T.
and Dement, W.C. (eds)
Principles and Practice
of Sleep Medicine, 3rd
Edition, Philadelphia:
W.B. Saunders, 2000,
1251-1257.
Evaluating Sleepiness
Merrill M. Mitler
Mary A. Carskadon
Max Hirshkowitz
Exces ive leep ine s durin g work activiti es is a se ri ou , potentia l\ li fe-t hrea tenin g conditi on th at affects
not o nl y lee py indi vidu al but also their fam ilies, coworke r , a nd society in ge ne ra l. The current conceptu a li za ti on of sleep regu la tion in vo lves two processes:
one p rocess is ci read ia n, a nd th e o the r is homeosta tic.
The effect of th e e processes o n se lf-re ported, bio logica l, and behaviora l meas ures of sleepiness is a topic of
con tinuin g re ca rch . WitJ1 th e growth a nd increas ing
inter t in Jeep d i o rd e rs, tools are need ed not onl y
for co nducting resea r h but also for cl ini ca ll y assess ing
patient for I ep ines . It is helpful to rem ember that
a ll too l have op tim al u
and limita tions. Alth ough
o ne may u ea hamm er to fas ten sc rews, a sc rewdrive r
wo rks better. Thu s, o ne s hou Id co nsid er th e assessment
g al w he n hoo ing a te hniqu e, consid er th e advantage a nd limitatio ns, and ca refu ll y fo ll ow specific eva lua ti o n proto o l .
T he fo u s of this cha pte r is clini ca l assessme nt;
th 'refo re, s pe ia l a tte nti on is d irected to three s pecifi c
m a urement i s ues . The firs t iss ue rela tes to individual d iffere n
in m eas ure m e nts o f wit hin-s ubj ec ts
ompa ri ons v r us betwee n-subj ects co mpari sons. For
a mp\ >, if the in rea e in leepiness ca n be precisely
mea ur d in a before-a nd -afte r ex pe rim ental d es ign,
the initi a l a lu c for o ne person w ill exceed the fina l
va lu e fo r ano th er. o nseq uentl y, thi s superb m e tri c
for indexin g relative slee piness is unable to establi sh
wh th ' r the pa ti ' nt in yo ur office is excessively sleepy.
The s o nd iss ue co n e rn elf-repo rt. In a clinica l
ituation, a ra ti o na l, e lf-aware, objective, sc rupu lously
hone t individual w ho i a good hi sto ri an and has no
ag nd , o th e r th an obta inin g trea tm ent for affliction
till p re ent a few prob lems in volving impairm nt
of e lf-a ·e m nt due to chroni c slee piness itself. Of
cour. , thi · bes t asc s ena ri o is rela ti ve ly unco mmon .
Wit h in rea s in g freq u n y, I ep s pecialis ts a re be in g
as ked to mi1kc i1 SS ' s m ' nts for regul ato ry and judicia l
pu rpo cs, so Fara mete rs of te tin g have becom e mo re
ru idl.
Th e third iss ue i that cl ini a l tes ting of sleepiness
u uall in o lves tes ting dur in g th e daytime. A large
numb r o f sludi s and nor ma ti ve d a ta ex is t for ph ysiolog i a ll ba ·cd metric of d ay tim e slee pine s. lf it is
lini ,i ll y nc c ssa r to a ssess lee p in ess durin g th e
night, such as in shift workers, the choices of valid a ted
tools are genera ll y limited to perform ance tes ts. Althou gh ph ysiologica ll y based m e tri cs can read il y be
used to detect nighttime drops in alertness in normal
and slee p-d eprived volunteers, the guid elines as to
w hat d egree of sleepiness is pathological during the
ni ght h ave not been establi shed; it is normal to be very
sleepy at 4:00 AM.
O ne traditional conceptualization for characteri zin g
sleepiness invol ved three factors: physiological sleepiness, m anifes t sleepiness, and introspecti ve sleepiness. 1
Thi s m odel provides a useful orga ni za tion al d ev ice for
understandin g sleepiness m easurem ent, but diffe rent
m easurem ents may index quite different (a lth ough related) ph e nomena. Phys iolo g ica l slee pin ess ca n b e
thou ght of as the und erlying biological drive to sleep;
conseq u e ntl y, th e primar y ind ex is th e s p eed w ith
wh ich an individua ls fa lls asleep . Ma nifes t sleepiness
ca n be considered from three p ersp ectives: behavi o ral
s ig n s of s lee piness, ina bility to volition a ll y re main
awa ke, and perform ance d eficit on p sychomotor or
cognitive tasks. The common threa d is th e tra nsform ationa l effect of underl yin g sleepiness o n outward behavior and abiliti es. Fina ll y, introspective slee piness
concerns an indi vidua l's self-assessm ent of an interna l
state. Alth ough the manifes t and introspective measures may s tem from th e sa me und erl y ing dri ve s tate,
individua l differences fac tor in and m odify the measurabl e phenom en a. It is not me rely ｩｬ ｯｧ ｩ ｣ｾ ｬ＠ to. attempt
to use th ese measures interchan gea bly; 1t mi sses th e
importan ce o f the differences between th em .
PHYSIOLOGICAL SLEEPINESS
Multiple Sleep Latency Test
If slee piness is co nside red .a n:o.tiv ati onal drive s ta te,
the rap idity with wh ich a n md1 v1dua l fa l!s as leep ca n
be used to evalu ate th e intensity of the dnve. As su ch,
slee p d ep riv ation d ecreases la tency to sleep o n .subsequ ent slee p opportun ities. Awake-depende nt drive for
slee p bui ld s across th e norm al. wakmg da y, is o p.posed
by a circa d ian-depend ent d.nve for ｡ ｬ ｾｲ ｴｮ ･ｳ＠
111 the
eve nin g, and th en rapid ly n ses to m ax imal leve ls as
1251
This. m ate ri al w as. c10pi e{j
atth.e NLM and m ay t>e
Sut>je.ct USOo;py righit Laws
1252
ABNORMAL SLEEP
sleep dep rivation and circad ian factors combine in the
ni ghttime h ours. 2 During the normal nighttime ho urs,
the physiological drive to sleep qui ckly reaches m ax imum levels, and sleep onse t becom es almos t immediate wh en sleep op portunities are provided . Ph ysiologica l sleepiness is standardly indexed u sin g the multiple
sleep latency test (MSLT). An MSLT is a series of nap
opportunities (four to six) presented at 2-h intervals
beginning approximately 2 h after initial (m orning)
awakening (fo r details, see Carskad on et al.3). Indi viduals undergoin g an MSLT are instructed to allow themselves to fa ll asleep or to not to resist fa lling asleep. Subjects
are tested under standardized conditions in their stree t
clothes and are not permitted to remain in bed be twee n
nap test session s. Similarly, subjects should not engage
in vigorous pretest activity becau se it will alter tes t
outcome. 4 Standardization of testin g conditions is necess ary and criti cal to obta in reli able res ult s .5 Sleep
rooms should be da rk and quiet during tes ting. Electrophysiological p aram eters need ed to detect sleep onse t
and score sleep stages are reco rded during n ap opportunities. Recordings include central (required ) and occipital (very strongly reco mmend ed) electroence pha lograms (EEGs), left and right eye e lectro-oculograms
(EOG s), and s ubm enta lis e lec t ro m y o g r a m (EM Gs ).
MSLT guidelines also ca ll for monitoring respira tory
flow and sounds in patients kn own to snore (Table
104-1 ). In a series of elegant studies, the effects of age,
partial sleep d epriva tion, and disorde rs of excessive
somnolence w ere w ell characterized .0-9 Key con cepts
concerning homeostati c influences on sleepiness deri ve
directly from research with MSLT. MSLT dem onstrations of the cumulative na ture of sleep debt, th e increased slee piness durin g a dol esce n ce p rodu ced by
sleep restriction, and redu cti on in sleepiness after sleep
extension provide the fo und ation fo r unde rstandin g
the interaction between sleep and w ake fulness. It has
also been noted that circadian influen ce h as been no ted
in sleep latencies on n ap opportunities scheduled in
the mid-afternoon for subjects wh o were no t a lrea d y
n ear m aximum sleepiness o r alerh1ess.10
Two protocols exist for condu ctin g the MSLT: clini ca l
and research (Fi g. 104-1). These two protocols diffe r
w ith respect to how mu ch accumula ted slee p is a llow ed if an individua l fall s aslee p on a nap o ppo rtu nity. In th e research ve rsio n, accumul ated sleep is mini mi ze d by awakenin g th e s lee p e r a ft er s lee p o nse t
Table 104-1. MULTIPLE SLEEP LATENCY TEST
RECORDING MONTAGE
Physiological Activity Recorded
Left o r rig ht ce ntra l EEC (C3 o r C4)
Le ft o r rig ht occipita l EEC (01 o r 0 2)
Left ho ri zo nta l o r obli q ue EOG
Ri ght ho rizo ntal o r obli q ue EOG
Ve rt ica l EO G
Submentali s (chin ) e lec tro m yog ram
Electroca rd iog ram
Res p irato ry fl o w, as need ed
Respi ra to ry so u nds, as need ed
EEG, electroence pha logra m; EO G, electro-a ulogra m.
No Smoking No Vigorous ａ｣ｴｩｶｾ＠
Prepare for bed Biocalibration
-30 m
-10 m
SSS
i
•
-15 m
-5
0
111
Assume comfortable "Please lie quietly1keep your eyes
position
closed and ｴｾ＠ to fall asleep"
• •
.j'-__,.__
-45 s
LightS·OUt
ＮｊｲｾＬ＠
-30 s
1st epoch
any sleep
•• ﾷｾＮ＠
m::==::::i
-5s
0
1st epoch
1st ｾｰｯ｣ｨ＠
Unequivocal sleep REM sleep
t_ _ •
Test Session Terminati on Rul es:
Experimental protoco l: End at T
Clinical protocol : nd at T 1+ 15 Ｑ ｾ＠
Either version, if no Jeep occurs: T0-t 20 m
Figure l 04-:-l. Specifi c procedu res for mu ltip le sleep ｬ ｾ
'
o ppo rtun 1t1es.
ｬｌ Ｇ ｮ ｣ｹ＠
ｬ ｬＧｾ ｬ＠
n ip
'
､ ｾｦｩｮ
･ ､＠ as (1) one cpo h of uncq ui vo al ' le p o r (2)
t ree epochs of s tage I slee p . Uncq ui vo a l sl 'P is a n
epoch of ｳ ｴ ｡ｾ ･＠ .2, 3, o r 4 o r rap id eye movc m ' nl (RE )
sleep . The chrn cal ve rsion a ll ow s m o re le ' to o ur
＿ ･｣｡ ｵ ｾ･＠ th e tes t atte mp ts to erve the d p I I ' f
d .
.
ua ro e o
rnd exmg slec in
P css an a tte m p tin g to un cove r abno rI
I
ma REM
· th e diffe r ·nti a l
. sf ee p tcnd cncY ( use fu I 111
d.1.agn os1s
o narcolcp y)
h t
.
.
· a
· t sc s1o n is th ' r ' fo r '
a II owe d to continu fo r 15 111111
·
f
a tc r lce p o n ct u ' in g
. .
t h e a b ove cnte n a (a su ·
·
.
h ti
I
mi ng it occurs) to d ' tc rmin ,
w e 11e r a s ec p-ons t R M sle p episod e w ill o ur If
no s eep on et occurs, th na p o ppo rh. .t . l ..
· b I
1111 y is ' rm 1na te d m ot 1 protoco l afte r 20 .
I
.
.
d
h
m
m
.
cc p la t •n y 1s
d e f me as t e e lap cd tim e fro th
the first 30-sec cpo h
d m
ta rt o f the l s t to
c co re as slee p SI '
I
.
no rm al adult co ntro l b.
. cc p a l n y m
fro m 10 lo 20 min .
Path ologica l sleepin ｳ ｾ ｩ ｾ ｣ ｴ ｾ ﾷ＠ ｲ ｾ ｮ ｧ｣ｳ＠
of less than 5 o r 6 min <> ｉ ｾ＠ ｭ ･ ｾ＠ as mea n I ' P la t ' n
no rm al and th e pa tl · ｾ ｣＠ t i ncic fa ll mg betw 'e n the
.
.
10 1og1ca va lues a re
,·d' ' :I
di agnosti c g ray a rea Th I"111 1. I
.
o ns1 r c a
a ve rsio n o f th ' M 1; r
re li abl y d is t·
· h·
.
mg ui cs pa tients
·ti
co ntro l subj ects with r 's c t l w 1 1 na ro l •ps fro m
e pisodes of REM slcc d ｾ Ｌ＠ ,
bo th th e nu rnb •r o f
ble 104-2 ).
p
tcd and le ' P la t ' n y (TaThe MSLT has p roved lo be
f
trea tm ent res pon c 11 11 It
u c u l fo r do um •ntin g
1
in css in pati ents ;, ho r a sot ca n rev a l r ' 'idu a l ' le• pｦ ｴ ｾ ｲ Ｎ＠ no lo nge r b ' in g 'le ' P
a fte r trea tm ent 1.1 Th ,
·
n 11 v1tyo f M LT t I .
.
ca l slee piness ma k s it e
.
o p 1 s1o log1:I
·
.
s pccia 11y us ' fu l f
pe rsistent slcep in cs in th ,
, '
o r c e lectin g
c pre um ab ly we ll -tre<1led
This materi al w as co pied
atthe NLM and may be,
Subj ect U:S rOopy r ight Laws
EVALUATING SLEEPINESS
1253
Table 104-2. MULTIPLE SLEEP LATENCY TEST RESULTS FOR 57 NARCOLEPTIC PATIENTS
AND 17 ASYMPTOMATIC CONTROLS
Individual Tests
Group
Narcoleptics
= 57
Fem a Jes 24
Males 33
Age 43.3 - 12.3
Controls
=
17
% Slep t
Sleep la tency
SD
Min imum
Maximum
% Slept
Slee p latency
ｾｮｩｭｵ＠
10:00 AM
Noon
2:00 PM
4:00 PM
6:00 PM
5-Test
Average
Score
100%
3.0
2.4
0.0
12.5
58.8%
14·3
6.0
J.3
20.0
98.3%
2.9
3.6
0.0
20.0
100°;.,
2.4
3.0
0.0
]8.0
100%
2.4
2.5
0.0
15.0
96.5%
4.0
5.1
0.0
20.0
99.0%
3.0
2.7
0.6
14.1
3.5
0.9
2
5
58.8%
13 7
·
6.1
0.3
20.0
70.6%
12 2
· ·
5.7
2.5
20.0
76.5%
12 6
·J
5.2
2.5
20.0
52.9'Y
o
J4?
·6.1
3.3
20.0
63.5%
13.4
4.0
4.8
REM
0
0
0
20.0
0
.
n
ax1mu1
.
.
.
.
N on S Hajdukov ic R. Narcolepsy. Diagnosis, treatme nt, and m anage me nt. Psych1atr C hn North A m . J987;J0:593
1
Adap ted from Mitler MM, es
'
606.
Its fo r the fiv e indi vidua l tests th rough out th e day, fo ll owed by th e average for a ll five tests and the numbe r
Data col umns are th e group! resu curred The first row o f data for each group is th e percentage o f the group th at actu a ll y fe ll as leep during
.
h'd1 REMs ee p oc
.
All oth er values arc in minutes.
of lest in .w 1
each ind1v1dual test.
Females 11
Male 6
Age 33.4 +: 9.9
M
.
ma conti nu e because of an occult
patient. Slee pmesds. dyer ineffective trea tm ent, poor
.
.d Jeep 1sor ,
comor b 1
t ent regimen or conco mitant
t the trea m
'
｡､ｨ･ｲｾ
ＱＺ ｣･＠
o . .
Therefore, assessment of sleep
11
oponfic medicatJO j rnnography th e night before
Ｐ
with the ｾ ｳ･＠ of ｐ ｢ｻＺｾｩｮｧ＠
a careful history of drug
0
M LT te ting and
h e essenti al. MSLT should not
u e for the past ｮＺｯｴ､ｲｾ＠
withdrawal, w hile seda tin g
be cheduled dun ng
gki netica lly active, or after a
. .
e p 11 armaco
med1 ca t1on ar 1 disturbed sleep. . . .
,
ni ght of profo.und ｾｯ＠ demonstrate an 111div1dual s unA . a ｴ･｣ｨｮｩｾｵ＠
MSLT has several ｩｮｨ ･ｲｾ ｮｴ＠ ｾ ､ｶ｡ｮﾭ
Ｑ ｮ ＺｳｾＬ＠
d rl ymg ｳ ｬ ･ｰ
d' t obJ·ective, quantitative ap. tis its irec ,
I
ta ge . T h e. ftr
thou ht that peo ple w io are not
roa h. It ts ge nera ll y
sgelves fa ll asleep; however,
P
11ake t1iem
.
.
.
sleepy anno t 1 .
. ·ng awake if sleepiness is
.
.
I
d in remain 1
o ne ca n succee.
hu s if a positive MSLT is one t ｩｾｴ＠
not ov ｲ ｷ ｨ ･ ｬｭｾｮ
ｧ Ｎ＠ T f 1 -positive tes ts are theore tia se tory, atten d e d yo Iｹｾｯｭｮ＠
indt. at s. s Ieep1nes , labora
ca ll y mirnmal. A full: ht before MSLT testmg discloses
gra m re orded ｾｨ･＠
ｮｾ＠
uantity. If the prior night sleep
prior I ep ｱｵ｡ｬｴｾ＠
ｾ｜＠ ｴｾ､＠
or disturbed , MSLT can be
· significantly disn P
. is also recommended to
t
D
screening
I
.
epiness is not pharmaco ogr h du led . rug
1
1
ca
s
e
·
I
·
log1
n ure the p h Y 10
ava il ab ility of normative va ues
de MSLT the test of choice
·1 all y indu ed. The .'
'
d rdi za t1on ma
and tc t tan a . . s for man y yea rs.
for a
sing lee p1ne
1
f Physiological Sleepiness
Other Measures o
Pupi/lography
..
d ize a re affec ted by expo1e
pupi
ll
a
ry
､
ｾ
ｬ
｢
｡
ｴ
Ｎ
＠
ｮ
'd ual' s a rousa l leve l. In a
Tl
.
. I d 'I t . h
an tn iv1
·ur to li ght ' n d . . idu al's pupils wil 1 a e, owＱ
ｾ＼＠ rk •ncd room, an ｾ･ｳ＠
sleepy and begins to fall
.
a
per
on
be
.
d beco me un sta ble. This
eve r, a 5 '
.
i stn t an
d
Ice ' the pu ptls o1 . nervo us system change an
｡ｾ ｮｾ ･＠ rcflc ts ｡ｵｴｯ
ｮ ｯｾＱ Ｑ＠ a potenti al measure. o.f slee p
., ea rched
sed in the ltn1 ca l as1
·1 1
try wa u
f
has bee n
.d
y i Pu pt om
d ' ts treatment o r many
l ·n •n . ( nnr olcpsy an
t
scss mcnl o
years at the Mayo Clinic. 16 Electronic pupillogra phy is
an objective m ethod for monitorin g the size of a person's pupil; however, it is difficult to co mpare one
subject with another. Furthermore, normative data are
not available; consequently, the techniqu e h as not com e
into ge neral u se for clinically eva luating sleepiness.
Electroencephalography
Computerized quantitative analyses of EEG waveform features seem an obvious approach to assessment
of centra l nervous system arousal level. It h as lon g
been thought that EEG d elta activity ca n be u sed to
index sleepiness. Sleep-related EEG d elta activity increases in response to experimental sleep deprivation. 17
Hasan et al. 18 reported EEG correlates of drowsiness
usin g computerized analys is. In essence, the MSLT uses
EEG m a rkers (macroarchitectura/ features) of sleep onset
to quantify sleep iness. It is reasonable to ex pect th a t
subtl e waveform pa ttern s (111icroarchitect11re) could provide a sensitive m etri c. A lpha EEG freq uen cy decreases
and amplitude increases occur just before sleep on se t
(marked by alph a EEG disappearance). Eve n furth er
refinem ent u sin g event-related potentials to directl y
ind ex th e neurologica l reactivity to sen sory stimu li ha s
been ex plored as a way to assess slee piness. Although
these approaches hold promise, the la ck of techniqu e
s tandardi za tion a nd the absence of norma ti ve data
limit th eir clinica l usefulness. In addition, the high
deg ree of be tween-subject variation makes it diffi cult
to co mpare res ults between indi vidu als. Finally, continuou s EEG measures may not be as sensitive to episodes
of sleepiness as co ntinuou s observation by a trained
observer. Severa l inves tiga tors repor t tha t continuous
EEG identifi ed fewer episod es of sleepiness 19 and was
less predictive of performance lapses than continuou s
video monitorin g. 20
MANIFEST SLEEPINESS
Maintenance of Wakefulness Test
Procedures u sed to co ndu ct the 1T1ainte nan ce of
wakefulness tes t (MWT) are similar to th ose u cd for
Th is. m at e r i a I w as. oopi ed
1254
ABNORMAL SLEEP
th e MSLT. 21 Th e m ajor d iffere nce is th e instruction
given to the test subject. The person being tested is
told to attempt to remain awake. In this m ann er, the
MWT is u sed to assess an indi vidu al's capabili ty to not
be overwh elmed by sleepiness-that is, the fun cti onin g
of the underlying wakefulness system is assessed. If
the wakefulness system fa ils, sleepiness becomes manifes t. This laboratory situ ation p arallels circum stances
in w hich sleep on set occurs inad vertently while a person is passive and sedentary in a non stimul ating environmen t. In the MWT, there is no task other than
to rem ain awake. During th e MWT, an indi vid ual is
m onitored for EEG sleep onse t during fo ur to six sessions, sch eduled at 2-h intervals beginning 2 h after
awa kening from the p revious ni ght' s slee p. In stu d ies
th at compared MWT and MSLT sleep latencies, as expected, subj ects we re fo ui:'d to take longer to fa ll asleep
w h en instru cted to rem am awake th an w hen told no t
to resist sleep .
A m ajor criticism of MWT re lates to th e w ide variety
of p rotocols u sed . MWT session len.gth has not been
well standardized; 20-, 30-, and 40- mm tests h ave been
u sed, with the lon ger tests devised to avoid ceiling
effects. Also, a m ajor d rawback in the u se of MWT has
been the lack of n orma ti ve d a ta; however, this situation
h as ch an ged .22 Table 104-3 presents ｮ ｯ ｲｭ ｾ ｴｩ ｶ･＠
d ata
u sing 40-min MWT trials fo r 64 asy1'.1I?tom at1c c? ntr.ols
w h o were m edicall y h ealth y on chmcal examina tio n
and free of sleep disorders by nocturnal polysomn ographic criteria. Table 104-3 also p resents projected
norms if 20-min trials are u sed .
Rem aining questi ons include the effect of acute sleep
deprivation, age, time of tes tin g, and dru gs on MV\'.T
p rofiles. N evertheless, the 1'.lWT ｾ ｡ｳ＠ proved u seful m
evaluating treatment effects m pati ents w ith na rcolepsy
and slee p-re late d brea thing d isord ers . .ｂ ･｣｡ｾ
Ｑ ｳ･＠
th e
MWT p oses the questi o n of wh ether sleer_mess is ove rw helming, the tes t h as attrac ted the attention of regulatory agencies. With the growing interest in ｳ ｬ ･ ｰｾｮ ･ｳ＠
and public safety, dem and fo r tests to a.ssess ｳ ｬ ･ ｰＱｾ ･ Ｎｳ＠
h as increased . Indeed, th e Fed eral Av ia ti on Adm1mstra ti on recogni zes the MWT as a mean s to dete rmine
w h ether n on co mmercial pilo ts ca n be li censed after
treatment fo r sleep ap nea. 23 MWT measures often re-
vea l improvement in trea ted patients who continue to
be p hysiologically sleepy; thu s, MWT is omctimc
thought as a way of ex tendin g the ensitivity ran ge of
MSLT. 24 It shou ld be noted, however, that MSLT and
MWT do not correlate we ll in pat ients co mpl a ining of
excessive sleepi ness. 2 ' Ma ny patients w h o w ill fall
a leep rapid ly w hen not res i ting sleep can till retai n
the abi lity to re main awake if they desir . Und erl y in g
neurophysiological mechani sms for mainta ining a lertness are q ui te d istinct fro m those th at regulate a nd
coordinate sleep.
Performance and Vigilance Tests
Ma ni fes t sleepiness ca n be meas ured u in g a va ri ety
of pe rformance ta sks. So me of these te ts attempt to
m.easu re cogni tive slowing (e.g., the di git ymbo l ubst1tu tion tes t), w hereas others address a lte ratio n in
｡ｴ･
ｾＱｴｩ ｯｮＮ＠
Aro usa l and attention ha ve traditi o nall y been
d 1ff1cul t to tease apart; th erefo re, it is no t urpri in g
that long, experimenter-paced, mon o tono u tasks that
tax the subject's endurance a re se n iti ve to sleep lo .
Such tes ts are ca ll ed vigiln11ce tests. The c tests ofte n
a tte m p t to m im ic the te diou s, pallin g itu at io n of
wat.chm g fo r bli ps on a ｲ｡､ｾ＠
sc reen or for hip o n th e
ｨ ｯ ｮ ｺｾ ｮ Ｎ＠ ｾｳ･
ｳ ｭ ･ ｮ ｴ＠ of vigil ance with non stimu la lin g
tasks is chrn ca ll y re levant in patients with di orde rs of
sleep
and arousal. Rega rd less of the te t u cd , cvc ra I
.
1mp?r tant measure me n t iss u es ex is t. The la ndm a rk
stu d ies, co ll ectively labe led The Walt r Recd xp ' ri men ts (na med for the institute in w hi ch they we re
co nd ucted) invcsti g.a tcd, among other thin gs, th e ' ffel cts of . sleep. depriv ation on perform anc .20 27 From
t 1ese p 1o nee nn g stud i s 1·t b
k
. '
eca me cl ar th a t tim eon-tas.' ｲ ･ｳｰｯｮｾ＠
slowmg, and res ponse la sin we re
a; ex clesse nti a l. fac tors in s11stni11 ed ntte11tio11 ta sks Ｈｦｾｲ＠
.
f
ient rev iew, see D in ges and K 'bb 28 ) A
. .
n s .
va n ' t o
per for mance, vigil ance and su t . d
.
'
amc ｡ｾ ｴ ｣ ｮｴＱ ｯ ｮ＠ le l
a re ava ilab le.29-31 H
·· ·
owcver, the prese nta ti o n mode lit
sens1t1v1ty, usefu lness, and ty
fd
.
'
p o . ata ava il able va r
co nside rabl y amon tc t
and the mea nin gf gl . s. f ｯｲｭ｡ｴｩｾ｣＠
d a ta a r limited,
.
u nes o co mpa n on b l
. d.
v1d uals ca n be d 1' ff'icu It to valuate.
cw n 111 1-
Table 104-3. MAINTENANCE OF WAKEFULNE SS TE ST SLEEP LATENCY NORMS (I N
FOR 64 CONTROL SUBJECTS
MINUTES)
40-Minute MWT Trials
M ea n
SD
Range
Trial 1
Trial 2
36.27
9.16
3.0-40.0
33.95
12.03
4.5--40.0
Trial 3
34.25
11.48
3.5--4.0
MWT
M ean
Trial 4
6.49
8.79
1.2 0.0
l'i.24
7.91
7. 1 o.n
20-Minute MWT Trials {Projected by Limiting Sleep Latency to 20)
Mea n
SD
Ra nge
19.08
3.06
3.0- 20 .0
18.09
4.37
4.5-20.0
18.39
3.90
3.5- 20.0
19.20
.
3 20
1.2- 20.0
18.69
2.6]
7. 1 20.0
.
Da ta from Doghramji K, M i tie r MM, Sa nga l RB, c t a l. A no rm a tive s tud y o f th e Ma intena nce of Wakefuln '% ｔＧｾｬ＠
Clin Neuroph ys io l. 1997;103:554-562.
MWT, Mainte nance o f Wa ke fu lness Test.
This m at eri al w as copied
atth e NLM and m ay b.e,
Sub.j ect U:SrOopy r ight Laws
M
.
.
( Wl ). l:htro1.'me ph ,1lo!.\r
EVALUATING SLEEPINESS
1255
Table 104-5. THE EPWORTH SLEE PINESS
SCALE ITEMS
INTROSPECTIVE SLEEPINESS
Profile of Mood States
. ed to asse s mood, the Profile of
Althou g h d es ign
d ·
J
(POMS) has ofte n been use m .seep
Mood Sta te I
. . 1 test design inclu ded a d 1menea rch 32 T 1e o n gm a
.
ｲ ｾｳ＠
·
. ss but it was elimin a ted becau se 1t
s10n for sleepme '
wi th other sca les. Sleepin ess
1
was fo un d ｦ ｯｰｾ＠
Ｚｾ｡ ｬ ･ｳ＠ most notabl y, Vigor (negal?ad severa . n and ｆ｡ ｴｩ ｧｾ ･Ｎ＠ To a lesser ex ten t, ｳ ｬ ･ｾｰ
ｩﾭ
t1ve), .con fu ｾ ｯ＠ 'd wi th increased scores on Depression
n s is ｡ｳｯ｣
Ｑ ｡ ｴ ｾ＠
Inte restin gly, the Con fu sion scal.e
a nd ａｮｧｾｲ＠
sea ｾｳＮ＠
more responsive to severe s leep1ma y b d iffe renti all y
le may be di ffere ntiall y more
ne s, a nd the Vig?r ｳｾ｡＠
d epri va ti on.33 The wo rn out
re ponsive to part1 a1 s .eep in the absence of m arked
y11dro111e of ｯｶ･ ｲ ｳＮ ｬ ･ ｲｾ ｧ＠ Globus34 is ch a rac te ri zed in
Jeep d eficit ､ ･ｳ｣ ｲｾ ･＠ t 1e POMS Fa tigue sca le m ood
0
la ngu age co m para e f f gue ca n occur ind epend ent of
descrip tors; howeve r, a i
leep iness.
ft
Stanford Sleepiness Scale
h Stan fo rd Sleepin ess Sca le (SSS)
For ma ny yea rs, t e
of 1·ntrospecti ve sleepiness.35
d m easu re
d
wa the sta n ｡ ｾ＠
h SSS ch oose one of seven sta teIf assessed curre nt sta te; the
lnd iv id u al tak in g t ｾ＠
·be t1eir
se 1
ment to d e en
. Tabl e 104-4.
ch o ices a re hown in . I d e its brevity and ease o f
1
Adva ntages of SShS fn c tutha t it can be ad minj ste red
. a nd t e ac
d
. .
adm in istra ti on .
epnv a t10n
1·ndu ced sleep
11
e
r11nenta
Y
.
d
d
t
repcate d iY· Ex P
. however, norm a ti ve . ｡ ｾ ｡＠
o no
in crca c SSS co r '
SSS to make chm ca l Judgxi t. It i d ifficult to .ust eos pective sleepiness be twee n
om pa re in r
me nt an d to c
indiv id u al
Epworth Sleepiness Scale
.
Sca le (ESS) w as d evelo ped
The Epwo rth Sleepin:ss E worth H ospital in Melby Murray Johns a tS t. e ｳ ｾ ･｣ ｩ ｡ ｬｩ ｺ･ ､ Ｌ＠ va lid a ted sleep
bou rne, Australi a. ｾｓ Ｎ＠ is : i ht ite ms th a t ask fo r se lfqu e ti o nn aire co nta1nrng g
THE STANFORD SLEEPINESS
Tobie 104-4. SCALE ITEMS
Question
Hypothetical Situation to Be Rated
1
2
3
Sittin g and reading
Watchin g te lev is io n
Sittin g, in acti ve in a publi c place (e.g ., a theate r or a
meeting)
As a passenger in a ca r for ·1 h without a break
Lying down to rest in the afternoo n w hen
circumstances permit
Sittin g a nd talking to so m eone
Sitting qu ietl y afte r a lun ch w ith o ut a lcohol
In a ca r, w h il e stopped for a few minutes in traffic
4
5
6
7
8
rep orted di sclosure of th e expectation of" dozin g" in a
variety of situ a tio ns. D ozing prob ability ra tings are
zero (0), slight (1), mod era te (2), o r hi gh (3) in th e eight
hy p othe tica l situ a ti on s sh own o n Tabl e 104- 5.
It is worth no tin g tha t in situ a tions 1, 3, 6, a nd 7,
on e is expli citl y sitting; in sih1 a tion s 2, 4, and 8, o ne is
presum ably sitting; an d in situa tion 5, one is lying
d ow n . ESS also differs from o ther tests in th a t th e
res pond ent is n ot bein g ask to interp re t hi s or h er
intern al sta te but ra ther to m ake a jud gm ent ab out his
or h er beh avior. Fu r th e rmo re, in a sen se, an individu al
comple ting the ESS is ratin g his or h e r drive to sleep in
p robability p rojecti ons. Thi s m ay ex plain w h y ESS h as
a s m all but s ta ti s ti ca ll y s ig nifi ca nt corre la tio n w ith
MSLT, a n objective index of sleep drive. Johns 36· 37 con du cted reli ability a nd va lidity studi es on 54 p a tients
w ith sleep -rela ted brea thing disord ers (b efore and after
trea tm ent with continuous p ositi ve airway pressure)
a nd 104 medi ca l s tud e nt control subjects. Sh1 den t contro l subjects h ad a m ea n sco re o f 7.6. Initi all y eleva ted
sco res am on g p a ti ents w ith sleep -re la ted brea thing di so rd e rs (mea n, 14.3) d ecl ined to the n o rm al ra nge after
trea tme nt (mea n, 7.4). ESS scores increase as a fun cti on
of in creasin g seve rity of their sleep-disordered brea th in g.36. 38
The p opula rity o f ESS s tem s in p art from its simpli city and brev ity. Thi s in conjun ction with th e va lidation
studi es h as m ad e it perh a ps the m os t comm o nl y admini ste red self-re p o rt scale for d ay tim e sleepiness. O ne
di sa d va ntage is the ques ti on abl e usefulness of th e test
w he n rea dmini ste red w ithin a b rief tim e inte rva l; con sequ e ntl y, it is n o t u se fu l fo r eva lu a ting circa di a n
rhy thm influ e nces o n sleepiness. In additi on, the sensiti vity to age, acute sleep di s turban ce o r d epri va ti o n,
a nd dru gs is no t kn ow n.
Scale Statements
Code
I
2
3
4
5
6
7
.t a le rt w id e awake
'
k bl
· ' an d vi a 1'
I . I level but not a t pea ' a c
Feeling ac11 v
Fu ncti oning a t a 11g ,
'
. . f II a le rtn ess, res po ns ive
to con centra te
kc no t at u
Re laxed, awa ' t a l cak, le t down .
. .
/\ Iittl foggy, no . pt lose inte rest 111 re m a ini ng
.iness, beg innidng o
Fogg
d ow n
.
.
awake, s 1owe
b ly ing down, f1gh t111g
.
. 5 prefer to
1cep1ncs ,
sleep, vvoozy .
Ice on c t soo n, los t s trugg le
Alm ost in reve rie, s p
to remain awake
PRACTICAL ISSUES
AND CONCLUSIONS
Befor slee piness is assessed, a va ri ety o f qu es ti ons
sh ou ld be considered , including w h e ther the goa l is to
establi sh (1) the presen ce o f sleepiness, (2) th e absen ce
o f slee piness, o r (3 ) ch a nges in sleepiness. ls testin g
be in g co ndu c te d fo r (4 ) cl ini ca l as sess m e nt, (5) resea rch, o r (6) lega l purposes? Is the re self- in te rest in-
Thi5 mate ri al w a5 copi ed
1256
ABNOR1\l!A L SLEEP
Table 104-6. COMPARISON BETWEEN TESTS FOR EVALUATING SLEEPINESS
Te st
Type of
Sleepiness
Evaluated
Repeated
M easure
Limit
Normal
Range
Available
MSLT
Pupillography
EEG
MWT
Vigil ance and performance
POMS
SSS
ESS
Physiologica l
Physio logical
Physio log ica l
Manifest
Manifest
Self-report
Self-report
Self-report
Sta nd ard ized*
Not lim ited
Not li mited
Standardized*
Not limited
Not limited
Not limited
Problemati c
Ye
No
No
Yes
No
Yes
No
Yes/ no•
Possible to
Fake
Sleepy
No
No
0
Yes:j:
Yes§
Yes
Yes
Yes
Possible to
Foke Alert
Yest
Unkn own
nknown
ｙ･
0
0
ｾ＠
Yes
Yes
*Stand ard protocol is four to s ix test sess io ns per day, at 2 h interva ls. Tes t sessions are somet·
child.ren), but thi s prndice i.s not recommended by the au th o rs. .
im es sched ul ed at shorter interval'> (e.g., for
tAssum1ng tha t an md1v1du a l 1s not ove rwhe lmmg ly s leepy, a ttemp tin g to re main awake can
d
.
:j:Assuming that an in d ividua l is physio logica ll y s leepy, not a ttemp tin g to rem ain awake w ·ll un ck rminc the test result.
.
t ma c it appea r ti t
1s present.
'
la overwhelming sleepin ' S'>
§Intenti ona ll y not attend in g or res ponding to the ta sk ca n m ake a n individu a l appea r s leepy.
llNormative d a ta were co ll ected from med ica l s tud e nts who often expe ri ence s leep depriva tion.
volved as part of a (7) primary or (8) seco nd ary
agenda? With increasing frequency, sleep specialists
are being asked for opinions in lega l cases involving
accid ents or disability claims and are often pressured
to render opinions concerning "fitness for duty." In
su ch cases, objective testing is criti ca l because there are
situational demand characteristics. Furthermore, a normal test result does not guarantee fitness for duty.
Table 104-6 shows some characteristics of the tests
described in this chapter. Ideally, physiological, manifest, and introspective sleepiness should be assessed .
In general, if an individual claims to be sleepy and th e
goal is to demonstrate sleepiness, the MSLT is the best
confirmatory tes t. If an individual claims no t to be
sleepy and the goal is to demonstrate an abi li ty to
remain awake, MWT has ce rtain adva ntages. For clinical purposes, self-reported measures combined with
MSLT have long been th e sine qua non for es tablishing
sleepiness. Sometimes, however, in cases involv ing severe sleepiness, MWT ca n demonstrate improved alertness after trea tm ent, whereas MSLT shows little or no
change. Such individuals continue to be pathologically
sleepy, but th ey are not overw helmed by it during the
brief tes tin g interva l. The relation between this pattern
of change and performance or behavio r requires further study.
The dangers posed by excessive sleepiness ar becomin g increasingly apparent. The National Co mmission on Sleep Disorders Resea rch 39 enum era ted a substanti al li st of industri al and transportation accidents
directly or indirectl y related to sleepiness. Although it
was originally th ought th a t sleepiness stemmed from
th e accumulati on of bl ood-bo rn e neuro to xin s, su ch
substances have not been clearly id entified. The sea rch
co ntinu es for sleep-indu cing peptid es (contemporary
descend ents of th e hypo th esized neu rotox ins); however, a conveni ent reli able blood tes t for sleepiness has
ye t to be developed. Nevertheless, evalu ati on techniques ca n assess not onl y the und e rlying physiologica l
drive to sleep but also its subjecti ve, internalized co nsequences and its behav ioral manifes tations.
References
1. Carskadon MA, Dem nt W The
.
what docs 1t measure? Slee
. . multtplc sleep latl•nc ' test:
2. Carskadon MA A b
P· 1982,5.S67- 72.
' cc o
Labyak E
'ct al. 1rcadian and homens tatic influ ences on sleep' 1 t '
at: S ixth Mee tin g of ti a ency in ado lescents. l'aol'r pr ''>ented
RI1 I
l e oc 1cty f
p
r
Yt 1ms; May 1998· Am 1
or 'cscar h on l3iollwic,1l
1
3 · C a rs-k a d on MA, Dement
'
ta 1sand
W
. Pi 'an ta t IOn, Jn ksonvtlk," l·la.
ｾｍ Ｌ＠ ct al u1tll•ltne'> for
the multipl e s leep laten cy t ｾｴｍ＠
s leep iness. Sleep. 1986;9.519- 524 (
1 ): a standard mea ... url' of
4 Bonne t MH, Arand DL SI
:
multipl e s leep la te ncy ｴｾｳ＠
eep1ness as n1 •asured by modified
act1v1ty Sleep 1998;21:477 113 vanes as a fun ction of pn'll'ding
5. Roehrs TA, Ca rskadon MA t. d
· an
to s leep SC1encc. Jeep. 1998·
. ard1/·'at·ion o f method : l''>'>l'nlial
6 Carskadon MA D
' 2 1.445.
t1on
d . ' , cnl .nt W · umulati , , ,
.
on ayt 1111c sleepiness p h
VC ff ClS of '>il'l'J1 re<,lrt C7. Ca rskadon MA , Demen t
syc ophys iology. 1981 ; 18: 107 11 1.
of behav io I
· Dayt1m ' le, 1·
R P ncss: quantifilation
8 M"tl M ra s tate. Ne uros i Biub 'h
.
t e r M, Nelson S, Hajdukov ic ｾ｡ｶ＠
cv. 1987; 11 :107 1 17.
ｾｮｴ＠
and mana gem ent. Psychi a tr . I" arcolepsy: diagno'>is trl'<1l
·
in North Am. 1987 · 1() ";LJ1
9. Carskadon MA 11 .
' ·
d a tim e I
. ' a1vey K, Duke I' ct I >
10 R. YI
s cep1ncss. Jeep. 1980 2"45'
a I ubcrt<1l r hangl''> in
' ·
60
. 1c lardson GS arsk d
lion m sic t · d '
a on MA, rav EJ ,
.
.
.
en en yin e ld erly and
' ct al. C1rtad1<111 v,rna 1982 5· 82 ｣ｾ＠
D ' .
- 94
young ,1dult '>UbJl'lh. C..ll'l'p.
ｮｴｗ
ｃＬ＠
a rskadonMA .
II. ｣ｭｾ
s lee pmcss in the s l
' Rt hardson CS E
.
.
Den
t WC
ecp ap nea sy nd
' · >-t 'ss1ve d,1 time
l Cn . ' ed s. Slee p A n,
romc. In: .uilk•minault C,
6
p ca Synd ron1cs. M '11ll1 I' ·' ( ' 1·f·
A lan R. Li ss; 1978:2
12 · La' mp he re J, Roehrs T w·
· ·
a1 " ' ,1 1 .
C PAP in ap nea I ' itti g R, 'l al R 'Co ,
13 USM
.
. iest. 1989·96 136
vcr of <1 lerlnl''>" ,1 ll'r
·
odaf1ntl in Na rco lc s '
1367.
1zed tria l of m d f. . p Y Stud y rou (US
Jenee in ｮ｡ｲ ｣ｯ ｬ ｾ＠ ｾ＠ inti for th ' treatment p
• M SC). Random 14. Zo n ck F R I psy. Ann curol. 1998"4Jof patholog1lal '>nmno' o 1rs T, onwa W
, 8 97.
Y , ct a l Eff. t f
ryngoplasty on th
a pnca s d .
e da ytim e hi 'epi1 , ｾ ｣ ｳ＠ o uvulopal.itoph.i
yn 10 mc. Bull Eur Ph ·
le<.,s •h'>O ' iatl'd with ..,ll'l' l
15 ｓｾ ｨｭＱ､ｴ＠
HS, Fortin L. El 'ctr ;s.1opathol Respir. 1981· 19 ·600
a1ousal. In G uill •
l ni c pupillo,
h
'
·
a ult
ed SI
grap y 111 d1<.,ordl' r" of
llldl ca t io ns a nd ｾ＠ e m1n
I
'
· eep1ng d W
1982.127- 143
cc1 n1qu es. Menlo l'ark a_n
,1k1ng 1)1..,ordl'r<.,:
' altf: l\dd1..,on -Wl'"il' y;
16. Yoss RE M · . N
' oye1 J, Ogl' KN Th
method to 1n casur , d
·
' pupillog
1969;19:921- 928 c
｣ｲ･｡ｾ
､＠ levds of war,1'.n and narrnll'Jl'> : ,1
17. Borbc ly AA B ·
J...dulne..,..,. l'uro logy.
.
' a um a nn F B·1
e ffect o n sleep sta
'
ande1s I) ' l 1
trocncep halog r · gcs, and EE , ｰｯｾ＠
j1,· ｃＮＬｬ Ｇ ｃｊｾ＠ lll' pnv,1t1on:
1 11 curnph ysiol. 1981' r· lCn<.,1l
y in m.1n l· ll'l
,'i I :481 -191.
This materi al w as copied
atth e NLM and may b.e·
W
wi
t
EVA LUAT ING SLEEPI NESS
·
K Va rri A e t al. Va li d a tion of co mpute r
18 1 lasa n j H1rvo ne n '
' .
.
d
·
' o l ra hi e patte rn s dunng drowsiness a n s 1ccp onana lyzcd p yg tai o r Clin Ncurophysiol. 1993;87: 11 7- 127.
set. Electroe nM
cc.pll Jg Lipsitz jj ct al. The slee p of long- ha ul
19 M1tlc r MM, 1 er
'
'
· . k d . s N Engl j Med. ·1997;337:755- 761.
.
ti u
n verM. . MM Mana g in g fa ti gue by drowsin ess dc tcc11
·nges
OF
a
ts
·
'
'
·
-1
·
d
· aI
20 · D 1
'
· I ·omi scs be rea li zed? 1 11r ln tc rnat1on
1
ti o n: ca n tee1Ｑｾ Ｐ＠ ｆ ｾ ｾ Ｚ ｣ ｾ ･ ｰｩｮ＠
Transporta tion: Coping With th e 24onference 0 b g
98· Fre mantle Wes te rn Au slralt a.
9- 13, 19 '
s · ty Fe ru ary
'
t KS Browman CP. Mainte nance of w akcHour ocie · .
21. Mi tie r MM, Gui avf r Y Ｑ ｾｧ ｲ｡ｰｨｩ
｣＠ techniqu e for eva lu a ti o n of
ｾＺｩ ･ ｮｴ ｳ＠ with excessive so mnol en e. Elecfulness test: .a po ｹｳｯ
trea tme nt effi cacy 111 P'
I1 1 Clin Neurop h ys1·01. 1982·53·658-661
, .
.
troence p .a og r . ler MM Sa nga l RB, e t al. A no rm a tive s tud y of
22. Doghra mJI K, Mit f W kefulness Test (MWT). Electroenccphalog r
the Maintenance o
a 03 55'562
.
h · I 1997;1 : ..-·
.
1111 curo p ys io ·d . . trati on (FAA) Slee p Apnca Evalu a ti o n
A
·ati
on
A
mint
s
'
.
.f.
.
I
1
23. Fe d e ra I .v
d
A ·ati on Administra tion s pec1 1ca t1 o n e t1
. n;
Spect. f1 a t1ons · Fe era v1 U.S. Depa rtment of Trans porta ho
tc r d a ted October 6, 1992 ·
1992.
.
JC Methods of testing for slee piness. Bcha v
.
24. Mitle r MM, Mil ler
Med . Ｑ ＹＶ［ ＲＱ
Ｚ Ｑ Ｗ ｬ Ｍ ｬ Ｘ ｾﾷ＠ M'tl er MM Di so rders of excessive slec pi25. a nga l RB, Tho m.as ' vet ability· to sta y a wa ke but docs not
nes : trea tment ＱＧｾ
ｾ＠ t. 1992;102:699- 703.
red uce sleepmes ·. A Goodn ow JJ . Impaired pe rfo rm a nce a nd
26. Williams !-IL, ｌｵｾ＠
h'o l Monogr J959;73( pt ＱＴＩ Ｚ Ｑ ｾ Ｒ ＶＮ＠
acut e sleep loss. Y
dcr slee p Joss a nd fati g ue. In: Kc ty
eds Sleep and Alte red State o f
27. Lubin A. Pe rfo rmfi·l ce ｵｩｾｌ＠
, Eva rts EV, Wt Hims Md · Wil.li a ms & Wilkins; 1967:506-513.
.
ess Balt1mo1e,
.
ff
f
.
on c1ou n :
NB Pe rforming while slee py: e ects o cx.pcn 28. Dinges OF, Kribbs
· . s In: Monk TM, ed. Slee p, Slee piness
mentall y-indu ced s 1cep1ncs .
1257
a nd Pc rform a n e. C hi ch es ter, En g la nd : j o hn W il ey & So n s;
199'1:97- 128.
29. Wilkinson RT. Slee p dep ri va ti o n: pe rfo rm ance tes ts fo r pa rtia l
and selecti ve sleep de pri va ti o n. In: Ab t LA, Reiss BF, cd . Progress in Clini cal Psycho logy. Vo l 3. Lo nd on, Eng la nd: G run e &
Stra tton; 1968:28-43.
30. I lirshkowitz M, De La ueva L, Herma n JH . Th e multi ple vigilance test. Bchav Res Meth Ins tr Co mp. 1993;25:272- 275.
31. Findley L, Unve rzag t M, Guchu R, et al. Vi g il a nce a nd a uto mobile accid ents in pa ti ents w ith slee p a pnea or narcole psy. Chest.
1995;108:619- 624.
32. McN air I M, Lo rr M, Dro p p lc ma n LF. Man ua l of the Profil e of
Mood Sta tes. Sa n Diego, Calif: Edu ca ti onal a nd Indus tri al Testin g
Se rvi ce; 1992.
33. Ho rne j. Dimensions to slee piness. In: Monk TM, ed. Sleep,
Slee piness and Pe rfo rm a nce. Chi cheste r, Engla nd: john Wil ey &
Sons; 1991: 169-'l 96.
34. G lobu s CG. A sy nd ro me associa ted w ith slee ping la te . Psychosomati c Med. 1969;31:528- 535 .
35. Hodd es E, Za rcone V, Smyth e H, c t al. Q ua ntifi catio n of sleepiness: a ne w a pproach . Psychoph ysio logy. 1973; 10:431-436.
36. johns MW. A new me thod for measurin g daytime slee piness: th e
Epworth Slee piness Sca le. Slee p. '1991;14:540-545.
37. johns MW. Reli abi li ty a nd fa ctor a nal ysis of the Epwo rth Slee piness Scal e. Slee p . 1992;1 5:376-381.
38. 1-lirshkowitz M, Gokccbay N, Iqba l S, et al. Epwo rth Slee piness
Scale a nd slee p-disorde red brea thing: re plica ti on a nd ex tensio n.
Slee p Res. 1995; 24:249.
39. Na tion al Co mmi ssio n on Slee p Disord e rs Resea rch. Wake Up
Am eri ca: A Na ti onal Sleep Al e rt. Vo l. 1, Executi ve Summ a ry a nd
Executive Re po rt, Re po rt of the Nati o nal Co mmi ssio n o n Sleep
Disorde r Research. Na tion al Ins titutes of Hea lth . Washin g to n,
DC: US Gove rnm e nt l' rintin g Offi ce; 1993 .
Thi.s mat e ria l w a.s c.opied
Merrill M Mitler