Section 8: Sleep Science and Interventions Flashcards
In what 3 ways can sleep be defined?
Sleep is defined: by duration, timing and quality
Describe some sleep statistics (for the US)
- 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
Describe human circadian physiology? What has the most potent influence on it?
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
What does melatonin do?
- 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
What is sleep pressure due to? What happens with insufficient sleep?
due to adenosine accumulation (counteracted by caffeine)
o Insufficient sleeping -> retain adenosine -> napping
What are the health impacts of disrupted sleep?
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
What are the effects of impaired sleep on CV outcomes?
o Increased sympathetic tone, endothelial injury, increased blood pressure, CV disease deaths
How does impaired sleep affect mood and cognition?
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
How might sleep impact on cancer?
o suppresses melatonin, immune system, dysfunction in transcription, aberrant DNA methylation.
o Correlates with breast, endometrial, prostate, colorectal cancer, AML
What are the 2 main sorts of sleep assessment?
o Objective: polysomnography (PSG or sleep study), or actigraphy
o Subjective: sleep diaries, retrospective assessments, validated questionnaires
When is Polysomnography indicated?
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
Describe the different stages of sleep:
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)
Other than PSG, what other objective assessments of sleep are there?
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
List some self-report sleep assessments/questionnaires:
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
What four signs of sleep disturbance can be identified from sleep assessments?
o <7 hours or >9 hours duration
o 1+ hours weekday- weekend difference
o Irregular sleep timing
o Daytime fatigue, difficulty waking
What are the STOP-BANG criteria?
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)
What changes in overall sleep patterns are recommended? eg duration, timing
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
Describe the ideal sleep environment?
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 :)
What routines around bedtime, diet and exercise should be recommended to improve sleep?
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
How can melatonin be used to improve sleep?
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
Describe treatment strategies to help with delayed sleep onset/difficulty initiating sleep?
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
Describe what can help with difficulty maintaining sleep/sleep fragmentation?
Use red-toned night lights if required/don’t turn on normal lights
Avoid evening diuretic beverages
What can help with early waking?
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
Describe how to manage jet lag from travelling east?
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
Describe how to manage jet lag from travelling west?
Prolonging the cycle so get late afternoon and early evening bright light, preferably outdoors
