Sleep & RestProf. Y.K. Wing

Department of PsychiatryThe Chinese University of Hong Kong

“Sleep is a natural repeated unconsciousness that we do not even know the reason for.”

Popper & Eccles 1977

Theories on the Functions of Sleep

Evolutionary theories of sleepHumoral theories of sleepBody restitution theories of sleepSleep and the motor systemSleep, memory & learning: cerebral developmentHeat conservation

Sleep & Wakefulness: Circadian rhythm

Circadian rhythm, “circa” = “around”; “dies” = day (Franz Halberg)Control of rhythm – internal clocks and external cues (Zeitgeber: cues)Paired suprachiasmatic nuclei (SCN) of the hypothalamus – pacemaker functionClock genes (1990’s)

Human Circadian PacemakerRegulation of circadian period in humans was thought to differ from that of other species, with the period of the activity rhythm… median 25.2 hours… in adulthood, and to shorten with age.

Now revealed that the intrinsic period of the human circadian pacemaker averages 24.18 hours in both age groups, with a tight distribution consistent with other species.

Czeisler CA et al Science 1999

Models of Sleep

1. Two-Process (S-C) Model2. Two Oscillator (x-y) Model3. Reciprocal Interaction Models of

the NREM-REM Sleep Cycle REM-on vs REM-off cells

Measurement of Sleep

Polysomnography measures electroencephalography (EEG) electromyography (EMG) electrooculorgraphy (EOG) electrocardiography (ECG)respiration

What is EEG?In EEG recording, the simultaneous activities of many cortical neurons are measured by extracellular macroelectrodes

Origin of EEGWhen thousands of neurons are excited simultaneously, the tiny signal from each cell sum up to generate one large surface signal. Asynchronous activity, on the other hand, produce irregular signals

Measurement of SleepPolysomnography measures

Electroencephalography (EEG) Electromyography (EMG) Electrooculorgraphy (EOG) Electrocardiography (ECG)Respiration

Sleep Pattern

Stage Features % sleep

Wake EEG activities at 8-12 c/s

I Drowsiness Activities 4-8 c/s, Slow rolling eye movements

5

II Light sleep

EES sleep spindles at 12-14c/s, Single high voltage multiphasic K-complex

50

III Deep sleep

Slow wave at 1-4 c/s about 25-50% of an epoch

5

IV Very deep sleep

Slow wave at 0.5-2c/s over 50% of an epoch, No eye movement

15

REM Stage I like EEG activities, rapid eye movement, absent or lowest muscle tone

25

Sleep pattern

Difference between NREM & REM sleepBegins with deepening NREM sleepInterrupted about every 90 min by REMSleep 4-6 NREM-REM cycles/night More REM towards morning

How much sleep do we need?

Individual variation8 hrs rule may not applySleep as essential vs luxury (cf food)Are we sleep deprived in modern era?Sleep deprivation: consequences

Variations in Sleep

age related changesintra- & inter-individual differences“long” & “short” sleepersnutrition and body weightmood changescircadian rhythmsdrugs

Sleep DisordersToo little sleep (DIMS, insomnia) eg. stress related, anxiety, depressionToo much sleep (DOES, hypersomnia) eg. sleep apnea, narcolepsySleep wake schedule eg. jet lag, shift workUndesirable behaviour at sleep (parasomnia) eg. sleep walking & terror, bed wetting, REM sleep behavioral disorder

Common Sleep ProblemsAge Sleep disorders

0 to 4 mo Night waking & feeding are developmentally appropriate

4 to 12 mo Night wakingDemand for nighttime feeding

2 to 4 yrs Disorders of Initiating & maintaining sleep

3 to 8 yrs Night terrors

6 to 12 yrs Sleepwalking, sleep talking

Adolescence Delayed sleep phase syndrome, Narcolepsy

Any age OSAS

Thiedke CC Amercian Family Physician 2001

Excessive Daytime Sleepiness (EDS)

Sleepiness that occurs at inappropriate or undesirable times or that interferes with daytime activities is general considered excessive by patients & clinicians

Aldrich MS., 1999

EDS

Sleepiness is pervasive in modern societyEDS is a frequent symptom that has many possible causesPrevalence rates of EDS may vary from 0.3% - 13.3%

(Schmidt-Nowara et al., 1991)

EDS – Common CausesYoung adults: their quantity of sleep is insufficient as a result of poor sleep hygieneElderly people: their quality of sleep is poorShift workers: repeated violations of the circadian rhythmOthers: they fall within the realm of pathology, whether primary, as in the intrinsic disorders of sleep, or secondary to a psychiatric, neurologic, or medical condition

EDS – PrevalenceAuthor Definition of EDS Prevalence

Karacan et al. 1976

Too much sleep 0.3%

Bixler et al. 1979 Sleeping too much 7.1%Partinen & Rimpela 1982

Excessive tendency to fall asleep during the day

3%

Lugaresi et al. 1983

Sleepiness independent of meal times

8.7%

Klink & Quan 1987 Falling asleep during the day 12%Schmidt-Noware et al 1991

Falling asleep always/often as a passenger in moving vehicle

13.3%

D’Alessandro et al., 1995

Consequences of EDS

EDS deleteriously affects work/school activitiesAffected social and/or marital lifeExhibits a negative socioeconomic impactIncrease the risk of a motor vehicle crash

Ohayon, MM et al, 1997

Average Sleep Duration at Different Ages

4 years10 years

Mid adolescenceLater adolescence

12 hours9-10 hours8.5 hours7-8 hours

Sleep Disorders in Children

25 % of children experience some type of sleep disturbanceSleep problems may be associated with difficult temperament in children. Instead of appearing sleepy, the overtired child may appear overactive & inattentive.

Wake up America, A National Sleep Alert January, 1993

Consequences of poor sleep

Cause child to be more vulnerable to physical illnessLimit parent-child bonding & later interactionAffect child’s self-esteem

Wake up America, A National Sleep Alert January, 1993

Consequence of sleep disorders

Sleep disturbance can produce a range of cognitive impairments such as memory, attention, visuospatial abilities and creativity as wellIn general population, poor academic performance was associated with sleep deprivationSerious psychosocial problems (including alcohol and drug abuse) have been described as a consequence of sleep disturbance in adolescents

Stores G 1999

Sleep deprivation & appetite

Total sleep deprivation in humans has been associated with hyperphagiaLeptin & ghrelin – hormones associated the central regulation of food intakeInadequate sleep seems to influence the hormones that regulate satiety & hunger in a way that could promote excess eating

Van Cauter E et al 2004

Sleep Apnea Syndrome (SAS)

SASAlso called Sleep-related breathing disorder

SymptomsLoud snoringEDSMorning dry mouth

Associated with Mortality 2-3 folds Risk of traffic accidents 2-3 folds Stroke Coronary heart disease Cognitive impairment

Type of Sleep Apnea

Central apnea thoracic and abdominal respiratory effect absent

Obstructive apnearespiratory efforts persist but rendered ineffective by upper airway blockade

Mixed apneathe episode begins with absence of respiratory effort followed by upper airway obstruction

Epidemiology of SAS

2-4% of general populationMale, obese, middle-agedSex ratio: 2-3:1 for male : female

related to hormone? Obesity?

Treatment of SASObstructive SAS

General Weight reductionSleep hygieneAvoid alcohol/sedative drugSleep position training

SpecificCPAPSurgeryDental appliance

Central SASRespiratory stimulants

Childhood OSAS

Causes: adenotonsillar hypertrophycraniofacial anomaliesneuromuscular diseaselaryngomalacia obesity

Sleep Walking

Sleepwalking: Definition

SLEEPWALKING consists of a series of complex behaviors that are initiated during slow wave sleep and result in walking during sleep.

Sleepwalking: Incidence/Prevalence

Between 1 and 15% of the general population.Most western studies reported 10-20% of healthy children have had at least one episode of sleepwalking. Above the age of 15 years, the incidence of sleepwalking is 1%.Equal distribution in both sexes.

Sleepwalking: Treatment

Precautions: Home safetyMedications (e.g. Clonazepam)Psychotherapy/Stress managementHypnosis?

Behavioral

Avoid sleep deprivation.Avoid alcohol.Stress-management techniques.

REM Sleep Behavior Disorder (RSBD)

RSBD

Symptomsviolent behaviors during sleepattempt to enact dreaminjury to self or bed partnerEpidemiology0.5%-1% of the elderly populationmale, elderly

RSBD in Hong Kong SRI in a community sample of 1034 elderly

0.8% reported history of sleep-related injury.

prevalence of RSBD of 0.38% (95% CI=0.01 to 0.76%). One subject had suspected RSBD

Wing et al & Chiu et al Sleep 2000

Etiologies of RSBDAcute

Toxic state

Withdrawal state

ChronicIdiopathicParkinson’s diseaseDementiaVascular / neoplasticFatal familial insomnia

Treatment of RSBD

Long-acting benzodiazepine: Clonazepam, effective in about 90% of patients

Other Medications: melatonin, tryptophan, antidepressants

Narcolepsy

Narcolepsy - ICSD

Is a disorder of unknown etiology, which is characterized by excessive sleepiness that typically is associated with cataplexy &other REM sleep phenomena such as sleep paralysis & hypnagogic hallucinations

ICSD 1990

What is cataplexy

Sudden symmetrical muscle weakness precipitated by emotion (mostly laughter)

DDX: convulsion, syncope

Narcolepsy In Hong Kong

Wing et al 1994 & 1998 100% DR2 & DQW1+ve in Chinese

Wing et al 2002 Population prevalence rate: 0.034% (95%CI 0.01-0.117)

Genetic BreakthroughLin et al 1999 Novel gene mutation of

hypocretin in canine narcoleptics

Chemelli et al 1999

Narcoleptic-like features in hypocretin knock-out mice

Nishino et al 2000 Low CSF hypocretin level in human narcoleptics

Peyron et al 2000 Loss of hypocretin-cell in human narcoleptics

Mignot et al 2001 Complex interaction of HLA association & hypocretin

Sleep wake schedule disorder

Sleep-wake schedule problemDelayed sleep phase syndrome (DSPS)

affect school / work / social function

Jet lag industrial catastropheShift worke.g. nuclear plant accident

Local Sleep Research

Sleep in Child & Adolescent

Mean Sleep Duration in Weekday

4

6

8

10

12

6 8 10 12 14 16Age

Hours R2= -0.549

P<0.001

510510510N =

holidayweekendweekday

95%

CI

10.5

10.0

9.5

9.0

8.5

8.0

Mean Sleep Duration

Weekday = 8.35 ± 1.36

Weekend = 10.05 ± 1.18

Holiday = 10.22 ± 1.06

Reported & Expected Sleep Duration

4

6

8

10

12

6 8 10 12 14 16 Age

Hou

rs

Reported

Ex pected

SSI = Reported Sleep Duration / Expected Sleep Duration

SSI < 0.8 = 23.3%

Sleep Duration

Childhood Insomnia

Difficulty in initiating asleep (DIS)Difficulty in maintaining sleep (DMS)Early Morning Awakenings (EMA)

10

7

1.9 1.7

9.7

0

2

4

6

8

10

12

1-2/few months 1-2/month 1-2/week 3-4/week >4 /week

Perce

ntag

e

ProblemPrevalence

(>3 times/wk)Sleep onset >30

min

DIS 3.6% 26.6%

Difficulty in Initiating Sleep

19

8.2

3.10.9 0.5

0

5

10

15

20

1-2/few month 1-2/month 1-2/week 3-4/week >4 /week

Perc

enta

ge

 

ProblemPrevalence

(>3 times/wk)Occurred in Recent 1 year

DMS 1.4% 84%

Difficulty in Maintaining Sleep

Sleeplessness among Chinese societies

HK Taiwan* China**

N 588 965 1365

Age (range) 12.3 (7-16) (13-15)14.6 (12-

18)

Frequency >3/wk >1/wk >2/wk >1/wk

DIS 3.6% 10.6% 27.2% 10.8%

DMS 1.4% 4.5% 31.9% 6.4%

EMA 1% 1.7% 22.3% 2.1%

Overall 5.4% 14.5% NA 16.9%

*Sleep 1995 18(8):667-673 **Sleep 2001 23(1):27-34

Chronic insomnia & school performance

Insomnia was the most powerful predictor of school failure, more significant than parental education and profession.The rate of school failure among insomniacs was twice that of non-insomniacs

Sleep Research 1990;19:1

Factors related to sleepless children

Infancy“Colic”Middle ear diseaseFrequent nighttime feeds

Early ChildhoodPoor bedtime routineInappropriate nappingStressful or undesirable sleep onset associations

Middle ChildhoodDifficulty getting to sleepNight-time fearsOverarousalAdvanced sleep phase syndromeParasomnia

AdolescenceSleep-disrupting disturbances (recreational, illicit)Circadian sleep-wake cycle disordersPsychiatric disorder

A Clinical Guide to Sleep Disorders in Children & Adolescents by Gregory Stores 2001

Sleep in Secondary school students

Sleep patternSleep durationWeekdays:*

Boys: 7.86 ± 0.94Girls: 7.64 ± 0.86

Weekend:*Boys: 9.53 ± 1.42Girls: 10.00 ± 1.08

283285 283285N =

Gender

FemaleMale

95%

CI

10.5

10.0

9.5

9.0

8.5

8.0

7.5

7.0

Weekdays

Weekend

*p<0.05

Sleep problems (1)

Prevalence of Insomnia:Difficulty in falling asleep: 28.6%10.2% need >30 min to fall asleepIntermittent awakening: 3.5%Early morning awakening: 3.3% no significant difference between gender

Sleep problems (2)

Other abnormal behaviorMouth breathing: 11.6%Breathing difficulty: 8.7%Snoring: 12.5%Morning dry mouth: 11.7%Non-restorative sleep: 14.7%

Summary of local dataSleep duration decreases across age Students tend to compensate their sleep during weekend which may suggest that they might be sleep deprived during school daysDifficulty to fall asleep was the most common problems among HK adolescents

Sleep deprivation among medical students

Prevalence of Insomnia (2004)

Female Male Overall

DIS* 39.9% 29.0% 35.5%

DMS* 17.5% 15.0% 16.5%

EMA* 14.0% 9.4% 12.2%

SL > 30 min 11.2% 8.9% 10.2%

EDS 14 17.2% 18.7% 17.7%

* “sometimes” or “always”

Sleep across medical years

0

2

4

6

8

10

1 2 3 4 5

Year

Sle

ep ti

me

(hr)

Weekday

Weekend

Factors associated with sleep deprivation

Risk Factors: Sleep Satisfaction index (SSI), morning unrefreshness, perceived stress & “sleep was a determinant of their aspect”Protective factor: adequate knowledge of sleep medicine

Conclusion

Sleep deprivation was prevalent among Hong Kong medical studentsSleep deprived students had significantly shorter weekday sleep hours but similar weekend sleep time than sufficient sleep group

Sleep in Adult

Epidemiology Study on Sleep in HK (1998)

Random Sampling of Telephone

Number

Random Sampling of Family Member

sample of households in HK from 1995 HK residential

telephone directories

Kish table selectionage 18 - 65

Structured Questionnaire including demographic data, sleep habit, life style, UNS & SRQ

Exclusion Criteria:Non-Chinesenon-residential numberfax machineage < 18 or > 65

9851 Success Interview

Prevalence of Insomnia in Hong Kong (1998)

Telephone survey (n = 9851; age 18–65 yr)

Li et al. 2002

Difficulty initiating

sleep

Difficulty maintaining

sleep

Early morning awakening

Insomnia

Pre

vale

nce

(%

)

Last month – 3 episodes of symptoms weekly in last month

Current – subjective report of frequent symptoms

0

5

10

15

20

25

18.5

11.8

7.3

3.9

8.96.8

9.3

4.5

Standardized prevalence of frequent insomnia

Age and sex standardized frequent insomnia prevalence of HK in 1998 = 18.4% (95% CI: 17.6% - 19.3%)

Median duration: 5 years

Age and sex standardized frequent insomnia (+fatigue) prevalence of HK in 1998 = 12.6% (95% CI: 11.9% - 13.3%)

Risk factors of Insomnia

UnemploymentLower economic statusAlcohol consumptionRegular medicationPsychiatric disturbance

Li RHY et al 2002

Sleep problems in Chinese elderly in HK

N = 1,034 elderly subjects75% occasional or persistent sleep disturbance38.2% insomniahigher rate of insomnia in female than malefactors associated with sleep disturbance

poor perceived healthpast history of smokingcurrent depressive disordersmore chronic physical illnessmore life eventsmore somatic complaints

2.8% had taken sleeping pills within a year

Chiu et al Sleep 1999

Good Sleep Practices - DOGo to bed at about the same time every nightArise at about the same time each morningExercise early in the afternoonDevelop a nightly sleep ritual (e.g. snack at bedtime)Make your bedroom dark, cool & quiet

Poor Sleep Practices – DON’ T

Drink caffeine in the afternoonExercise within 3 hours of sleepDrink alcohol in the eveningSmoke before sleep & during the nightUse the bed for activities other than sleep & sex

Behavioral Technique for Insomnia

Stimulus control therapyTo curtail sleep-incompatible behaviors & to regulate sleep-wake schedulesGo to bed only when sleepyBed & bedroom only for sleep and sexGet out of bed if unable to sleep for 15-20 min, & return only when sleepy again Arise in the morning at the same timeDo not nap during the day

Morin CM et al.1994.

Cont’dSleep restriction therapy

to curtail the amount of time spent in bed

Paradoxical intentionto persuade a patient to engage in his or her most feared behavior e.g staying awake

Sleep hygiene educationhealth practices e.g. diet, exercise, substance useenvironmental factors e.g. light, noise, temperature

Morin CM et al. 1994

General Strategies for Solving Problems

Rehearsal and planning sessions20 minutes in early evening; in a quiet room. Reflect on the day past. Encourage yourself with achievements. Consider problem areas and loose ends. Reallocate time to deal with these. Consider any other matters e.g. emotional, financial.. Write down the first or next positive step of action to take and when you will take it.If when in bed new thoughts intrude “refer” them on to next day.

Dealing with Frustration or Racing Thoughts

Do not try too hard to fall asleep.State to yourself with “sleep will come when it is ready”, that “relaxing in bed is almost as good”.Try to keep your eyes open in the darkened room and as they (naturally) try to close tell yourself to “resist that just for another few seconds”. This procedure “tempts” sleep to take over.Try to ignore irrelevant ideas and thoughts.Visualize a pleasing scene or try repeating a semantically neutral word (such as “the”) subvocally every few seconds.

Thank You