84 | NORTH & SOUTH| JUNE 2019
SleepGlossary
CHRONOTYPE
Thetendencytobea “morning
person”ora “nightowl”.This
canchangeaswegrow.CIRCADIAN
Sleepingis a biologicalprocess,
whichusesthis24-hourcycle.We
getjet-lagwhenit is outofwhack.
Somepeopleinheritaninnerclock
settoa differentcycle,which
causesdisastroussleepinghabits.STAGE 3 SLEEP
Deepsleep,alsocalled“slow
wavesleep”.Thishappens
mostlyinthefirsthalfofthe
night,andis thoughttobe
particularlyimportantforhealth
andwellbeing.Themostdifficult
timetorousesomeoneis when
they’reinthisstageofsleep.
Adultsspendaround15-25%of
theirsleepinstage3 sleep;this
diminishesslightlyasweage.REMSLEEP
Thestageofsleepassociatedwith
dreaming.Thereis paralysisof
almostallmuscles,rapidside-to-
sideeyemovement,andanactive
brainstate.Adultsusuallycycle
throughfourorfivecyclesa night
ofeachstate:stage1 (drowsiness),
stage2 (lightsleep),stage 3
(deepsleep),andREMsleep.REMSLEEPBEHAVIOUR
DISORDER
Lossofparalysisofthemuscles
inREMsleep,resultingin
theacting-outofdreams.NON-REMPARASOMNIAS
Conditionsthatcause
abnormalbehaviourssuchas
sleepwalking,nightterrors,
sleep-talkingorsleep-eating,
arisingwithinnon-REMsleep.
Sleepwalkingis commonin
childrenbutrarelypersists
intoadulthood– only1-2%
ofadultssleepwalk.
DRGUYLESCHZINER,NEUROLOGIST
ANDSLEEPPHYSICIANawakeoryouareasleep;thereisnoth-
inginbetween,”Leschzinersays.“But
inrecentyears,wehavelearnedthat
thisisnotthecase.Deepsleepandfull
wakefulnesslieattheextremesofa
spectrum,andimplausibleasitmay
sound,it ispossibleforustobeinboth
statesatthesametime.”
Alexhasgivenpermissionforhissto-
rytobetold,ashasJackie,a septuage-
narianwhosleep-rideshermotorbike;
Claire,a chronicinsomniac;andAdrian,
whofallsasleepwhenhelaughs.And
thenthere’sDon,a sleep-eaterfor 40
years.Desperate,heoncelockedhis
fridge– onlytofindonwakingthathe’d
eatenhisparrot’sbirdseed.Heis oneof
Leschziner’smoreintractablepatients.
Itmightsoundhilariousbut,topa-
tientslikeAdrianandDon,theirsleep
disordersarea life-alteringnightmare.
Agoodnight’ssleepiscrucialtoa
senseofwell-being.Youcan,thedoctor
pointsout,survivelongerwithoutfood
thanwithoutsleep;andyetitsimpor-
tancetomentalandphysicalhealthhas
beenslowtofindacceptanceamongthe
medicalestablishment.
Thisisbeginningtochange.Today,
sleepmedicineharnessesnotonlyneu-
rologistslikehimbutalsorespiratory
physicians,psychiatrists,cardiologists,
psychologists, ear, nose and throatsur-geonsandevendentists.Therangeof
specialistsworkingonsleepisa signof
itsimmensecomplexity.Basicques-
tions,suchaswhywedream,arestill
unanswered.
Onereasonmaybethepovertyoftools
attheresearcher’sdisposaluntilnow.
Theirmainstayis a machinefirstusedin
the1920s– theelectroencephalogram
(EEG).Itdefinesthedifferentstagesof
sleepbymonitoringtheelectricalsignals
ofthebraintorevealthetell-talebrain-
wavesof,forexample,deepsleep.Butthe
device,whichuseswiresstuckwithglue
tothescalp,islikeusinga snorkeland
masktoexploretheMarianaTrench,
saysLeschziner.Thetechnique,hesays,
“tellsusnexttonothingaboutwhatis
goingoninthevastdepthsofthebrain”.
Sleepmedicslikehimnowhavea
growingarsenalofnewtools.TheEEG
hasbeenjoinedbya rackofsensitive
devicesthatmeasureairflow,andchest
andbodymovements.Magneticreso-
nanceimaging(MRI)andpositron
emissiontomography(PET)lethim
see,howeverfuzzily,insidethebrain,
andgenetictestingislinkingsome
sleepdisorderstogeneticmutations.
“Thesetoolsweretotallyunimaginable
a fewyearsago.”
Althoughthisscienceisstillan
emerging one, Leschziner’s case