Section 8: Sleep Science and Interventions

Question 1

In what 3 ways can sleep be defined?

Answer 1

Sleep is defined: by duration, timing and quality

Question 2

Describe some sleep statistics (for the US)

Answer 2

• Average US adult: sleeps just under 7 hours/night
• 20% sleep less than 6 hours, 37% young adults sleep less than 7 hours
• Increase in short sleep duration across all ages
• Only 10% with sleep difficulties seek medical attention
• Indirect costs ~$60 billion – presenteeism, increased risk of long-term disability, errors/accidents
• Sleep disorder adjusted mortality risk 1.5

Question 3

Describe human circadian physiology? What has the most potent influence on it?

Answer 3

Human body rhythmicity 24.1-24.4 hours (-> easier to delay bedtime than wake earlier)
* Master control by suprachiasmatic nucleus in hypothalamus, entrained by internal and external stimuli – most potent is light
o Light brightness and timing is important
* Master clock coordinates with peripheral clocks (oscillators) in all cells, and also receives feedback from them
o Affects endocrine/metabolic systems as well as internal biological processes

Question 4

What does melatonin do?

Answer 4

• Melatonin: Produced by pineal gland, derivative of serotonin
  o Signals light is low: peaks 30 min before bedtime, stops after first light in morning
  o Inhibits SERT (sodium-dependent serotonin transporter) from circulating -> possible role in GI upset
  o Sensitive to melatonin suppression: bipolar, SAD, aging adults

Question 5

What is sleep pressure due to? What happens with insufficient sleep?

Answer 5

due to adenosine accumulation (counteracted by caffeine)
o Insufficient sleeping -> retain adenosine -> napping

Question 6

What are the health impacts of disrupted sleep?

Answer 6

Circadian misalignment due to behaviour ‘social jet lag’ – has adverse physical and psychological effects
o Metabolic disorders: includes higher cortisol & glucose, reduced insulin sensitivity, decreased testosterone, GH, dyslipidaemia, endothelial dysfunction
o Short duration/disrupted sleep correlates with obesity, metabolic syndrome, T2 diabetes, CV risk/mortality

Question 7

What are the effects of impaired sleep on CV outcomes?

Answer 7

o Increased sympathetic tone, endothelial injury, increased blood pressure, CV disease deaths

Question 8

How does impaired sleep affect mood and cognition?

Answer 8

o Results in less REM sleep (if not due to underlying disorder like sleep apnoea), increased slow wave sleep, decreased BDNF (triggers repair of neural tissue)
o Impaired learning, slower processing, alertness, worse memory, more distress and less able to extinguish fear
o Correlates with depression/bipolar, SAD, PMS, PTSD (if occurring prior to traumatic event) and TBI

Question 9

How might sleep impact on cancer?

Answer 9

o suppresses melatonin, immune system, dysfunction in transcription, aberrant DNA methylation.
o Correlates with breast, endometrial, prostate, colorectal cancer, AML

Question 10

What are the 2 main sorts of sleep assessment?

Answer 10

o Objective: polysomnography (PSG or sleep study), or actigraphy
o Subjective: sleep diaries, retrospective assessments, validated questionnaires

Question 11

When is Polysomnography indicated?

Answer 11

o Diagnostic for sleep disorders only:
o breathing related sleep disorders like obstructive sleep apnoea (OSA)
o narcolepsy
o nocturnal seizures
o periodic limb movement disorder
o REM sleep behaviour disorder
o Not required for circadian rhythm disorders, insomnia, NREM partial arousal parasomnias, nightmare disorder, restless legs
o Gold-standard for sleep staging – produce a hypnogram showing non-REM and REM sleep

Question 12

Describe the different stages of sleep:

Answer 12

o Non-REM has 3 stages
o Stage 1 is ~2%, when we enter sleep
o Stage 2 is ~50% - characterised by sleep spindles and k-complexes on EEG, logical dreams
o Stage 3 is 20-25% (slow wave/deep sleep) – characterised by delta waves
 usually occurs during first half of night
 Important for memory and body restoration

o REM sleep - ~20-25%
o First occurs 90-120 minutes after sleep onset
o Increase in duration throughout night, so most is second half of night
o Highest brain activity but movement mainly eyes only
o Important for memory, emotional consolidation
o Most dreaming occurs in this stage – often illogical

o (Infants enter sleep through REM not stage 1 non-REM)

Question 13

Other than PSG, what other objective assessments of sleep are there?

Answer 13

At-home studies mainly intended to assess OSA
Don’t stage but capture four measures
 respiratory movement and airflow
 Heart rate, or echocardiogram
 Oxygen sats

Actigraphs
Specific type of accelerometer – estimate sleep, validated against PSG, slightly overestimate sleep
Physical activity monitors often underestimate sleep

Question 14

List some self-report sleep assessments/questionnaires:

Answer 14

Sleep diary:
 Self-report over at least a week
 Provides data on time in bed, bedtime, time awake during sleep period, wake time, time out of bed

Retrospective mini sleep assessment:
 Captures average sleep patterns (bedtime, duration, waketime) on weekdays and weekends
 Perceived sleep quality

Single-item Sleep Quality Scale (SQS)

Pittsburgh Sleep Quality Index – extensive for subjective complaint of disturbed sleep

STOP-BANG for OSA

Epsworth Sleepiness Scale (ESS):
 8+ indicates excessive daytime sleepiness
 Assesses likelihood of falling asleep while doing quiet activities (scores 0-3 for each)

Adolescent Sleep Hygiene Survey (ASHS):
 28 item assessment to identify negative beliefs and sleep behaviours

Women’s Health Initiative Insomnia Rating Scale (WHIIRS):
 5 item assessment – can be used in teens/adults/men
 Identifies frequency of insomnia symptoms

Composite Scale for Morningness Questionnaire:
 Helps identify circadian preference

Question 15

What four signs of sleep disturbance can be identified from sleep assessments?

Answer 15

o <7 hours or >9 hours duration
o 1+ hours weekday- weekend difference
o Irregular sleep timing
o Daytime fatigue, difficulty waking

Question 16

What are the STOP-BANG criteria?

Answer 16

 Snoring
 Tired
 Observed apnoea episodes
 Pressure (elevated BP/meds)
 BMI>35
 Age >50 years
 Neck size 17+ inches male or 16+ inches female
 Gender: male
Scoring: 3-4 immediate risk, 5-8 high risk of OSA (or 2x yes AND male OR BMI>35 OR neck circumference)

Question 17

What changes in overall sleep patterns are recommended? eg duration, timing

Answer 17

 If insufficient sleep – extend
 If too much time in bed – limit
 Make changes slowly, or quality may be affected
 If sleep patterns are variable, - stabilise by establishing consistent waketime, then bring back bedtime as required
 A difference of up to 30 minutes is acceptable
 Aim to eliminate napping by extending the sleep period

Question 18

Describe the ideal sleep environment?

Answer 18

Ideally cool, dark and quiet
 Bodies do not regulate temperature as well during sleep
o Increasing peripheral cutaneous vasodilation prior to bedtime can be beneficial if poor circulation
o Cooling prior to bed useful if hot eg menopause
 Reduce noise/replace with white noise
 Remove sources of light at night, but introduce light on waking
o Reduce late afternoon/evening light exposure (table lamp rather than overhead light)
 Use bed for appropriate activities only :)

Question 19

What routines around bedtime, diet and exercise should be recommended to improve sleep?

Answer 19

 Bedtime routine 15-20 min before bed: Stop work/stimulating activities at least 60 min prior, replace with relaxing. Relaxation/mindfulness may be helpful
 Dietary: limit daytime and eliminate nighttime caffeine. Avoid alcohol within 3 hours of bed. Eliminate late night eating. Ensure adequate fluid and avoid high sodium at dinner – vascular tone. Address elevated BMI
 Exercise: Increase daytime PA. Individualise exercise timing – some struggle to sleep after evening exercise

Question 20

How can melatonin be used to improve sleep?

Answer 20

To stabilise sleep-wake cycle or recover from jet lag
 Acts as a phase shifter
 0.25mg can be helpful, take 3-4 hours before bed time
 Second dose can be taken 30-60min before if not sleepy

Question 21

Describe treatment strategies to help with delayed sleep onset/difficulty initiating sleep?

Answer 21

 Address environment, warm extremities
 Optimise light exposure
 Diet – high-carb breakfast, low-carb dinner
 Exercise – morning or afternoon better
 Wind down at least 1 hour prior

Question 22

Describe what can help with difficulty maintaining sleep/sleep fragmentation?

Answer 22

 Use red-toned night lights if required/don’t turn on normal lights
 Avoid evening diuretic beverages

Question 23

What can help with early waking?

Answer 23

 Ensure bed is warm enough
 Avoid bright lights until ideal wake time
 Increase afternoon/evening sunlight to increase melatonin
 Increase evening PA
 Use blue spectrum lights until 1 hour before bedtime
 Don’t have caffeine until 30min past ideal wake time
 Shift carbs to dinner time

Question 24

Describe how to manage jet lag from travelling east?

Answer 24

This is harder because you have to go to bed earlier and get up earlier (it’s harder to shorten the cycle): so get bright light at ideal wake time

Question 25

Describe how to manage jet lag from travelling west?

Answer 25

Prolonging the cycle so get late afternoon and early evening bright light, preferably outdoors