Sleep Flashcards
Components of sleep
- Behavioural state
- Marked by quiescence and low attention
- Recurrent and reversible
- Dreams and mentation
- Amnesia
- Expressions vary
Why sleep?
- Brain and body restoration
- Energy conservation
- Memory and learning
- Emotional regulation
- Housekeeping/ clearance
- Xie et al. (2013): metabolite clearance
- Yang et al. (2014): formation of dendrite spines
Structure of sleep
- Awake
- NREM (75%)
- Stage N1 light sleep (5%)
- Stage N2 (50%)
- Stage N3 deep sleep/ slow-wave sleep (20%) - REM paradoxical sleep (25%)
Characteristics of sleep cycles
- Alternate in a cyclical fashion
- Cycles gradually get longer (~70-100min to ~90-120min)
- Deep sleep reduces in later cycles
- Stage 2 and REM become longer across the night
Physiological changes during sleep
- Motor response
- Heart rate and blood pressure
- Blood flow to brain
- Respiration
- Body temperature
Neural basis of sleep/wake regulation
Superchiasmatic nucleus (SCN)
- Hypothalamus
- Controls circadian cycles
Ascending arousal system
- To stay awake
- Hypothalamus sends signals to stimulate cerebral cortex to maintain consciousness
- With the help of orexin neurons/hypocretin
Ventrolateral pre optic area (VLPO)
Releases NTs to switch from wakefulness to NREM by inhibiting activity in arousal centers
Two process model
- Process S: homeostatic process (tracking need for sleep by prior sleep and duration of waking)
- Process C: circadian process (tracking environmental time: light-dark)
- Interplay of these processes determines timing, duration and structure of sleep
Light in circadian rhythm
- Circadian pacemaker/ zeitgeber
- Synchronisation of retina and optic nerve
- Might have desynchrony in people born blind, shift workers, travellers, old people
Behavioral changes in sleep
- Reduced attention and response to visual stimuli
- May wake up from auditory stimuli
- May wake up from olfactory stimuli in stage 1
- Loss of muscle tone
- Memory impairment
Polysomnography (PSG)
- Electroencephalography (EEG): brain neurons
- Electroculography (EOG): voltage changes induced by eye rotation
- Electromyography (EMG): muscle activity from chin
Pros:
• Gold standards
• Precise rich information
Cons:
• Expensive, labour-intensive, training
• Short duration, lab based
• Intrusive (could interfere with sleep- i.e. first night effect, reversed effect for insomnia)
Actigraphy
Indirect measure (estimates sleep): algorithm used affects accuracy
Pros: • Affordable • User friendly • Ecological manner • Suitable for long observations • Good validation with PSG for time slept but not onset
Cons: • Indirect measure • Doesn’t detect moment of onset • Less information than PSG • Varying data depending on device, algorithm etc. (also need to use sleep diary)
Sleep quality questionnaire
Types: Pittsburgh Sleep Quality Index; Insomnia Severity Index; Jenkins Sleep Questionnaire
Pros:
• Convenient
• Cost-effective
• Benchmarked against diagnostic criteria
Cons: • Subjective • Retrospective • Recall bias • Further assessment required
Sleep diary
Sleep parameters: sleep onset latency, time in bed, wake after sleep onset
Pros: • Intuitive • Stable picture with 1-2 weeks of use • Information can help to reconstruct sleep experience Cons: • Burden on sleeper; missing data • Training for data collection • Training to interpret • Subjective and retrospective; recall bias
Apps and wearable tech
- Similar to actigraphy
- Algorithm and validation unclear
- Settling of sensitivity unclear
- Interaction errors (i.e. forget to wear)
- Interpretation hard (sleep stages not possible)
Sleep perception
- Sometimes objective sleep for insomniacs and normal sleepers overlaps but discrepancies are due to sleep perception
- Insomniacs have a high tendency to underestimate their actual sleep (overestimate sleep onset latency and underestimate total sleep time)
Hypotheses for sleep misperception
- Challenge of context
- Interpreting sleep as wake
- Worry/ selective attention
- Physiological arousal
- Transient awakenings
Clock monitoring (Tang et al., 2007)
- Clock monitoring lead to more reports of pre-sleep worry and longer sleep onset latency
- Found this even when they controlled by monitoring a digital display that wasn’t time
Driving drowsy
- 20% of all traffic accidents are sleep related
* 37% reported they have fallen asleep while driving
Cost of bad sleep
- Total: $6.6 billion (Canadian $) direct and indirect
* A&E: $31 billion: 7.2% of all accidents
Define epidemiology
Quantitative study of frequency, distribution, determinants and control of health problems and disease
• Cross sectional: snapshot
• Case-control: retrospective
• Longitudinal cohort: prospective
Basic concepts in epidemiology
- Exposure and outcome
- Prevalence, incidence, persistence, remission\morbidity and mortality rate
- Risk and odds ratio
- Cofounder and adjusted odds ratio
Pros and cons of epidemiology
- Representative
- Sufficient power
- Longer time frame
- Temporal order
- Expensive
- Few items for assessment
- Harder to use objective measures
How well is the world sleeping?
- Large percentage of people have insomnia complaints: 30-48% (Ohayon, 2005)
- Symptoms (37%) Diagnosis (5%) (Stewart et al., 2006)
Sleep deprivation and rat studies
Use plexiglas cage with rotating platform
Total sleep deprivation studies
- (TSD): baseline, experimental (36 hours of wakefulness), recovery
- Lost in one night: 2 hours REM, 2 hours SWS, 4 hours N1 and N2
Partial sleep deprivation studies
Postponed bed time and forced awakening (increase SWS and reduced N 1 & 2 and REM)
Partial: Sleep fragmentation
- Forced arousal: transient (doesn’t affect sleep duration); outright (decreases sleep duration)
- Leads to shallower sleep
Measures of cognition
- Simple attention
- Complex attention
- Processing speed
- Memory
- Reasoning and crystallized attention
- Verbal fluency
Findings of meta-analysis on short term TSD on cognition
- Significant negative effect in all cognitive domains (excluding speed and reasoning accuracy)
- High effect size for simple attention and vigilance; moderate for complex attention and WM; weak to no for reasoning and crystallised intelligence
Monk’s conceptual model (2012)
Provides possible outcomes of TSD that can affect poor performance
- Loss of motivation
- Cognitive rigidity
- Cognitive slowing
- Lapses and microsleeps
Complex tasks less affected than simple ones
- Vigilance hypothesis
- Controlled attention hypothesis
- Compensation hypothesis
Junior doctors and sleep deprivation
- 300% more adverse events if 5 or more extended shifts (Barger et al., 2006)
- Increased number of errors and time to complete task if hours of sleep decreased and fatigue increased (Eastridge et al., 2003)
- Effects of sleep deprivation are larger in non-physicians but doctors still had decreased performance (Philibert, 2005)
- Doctors with heavy call had higher speed variability than doctors who had alcohol before driving simulation study (Arnedt et al., 2005)
Hill’s criteria of causal inference
- Strength
- Consistency
- Specificity
- Temporality
- Bio gradient
- Plausibility
- Coherence
- Experiment
- Analogy
Associations with sleep problems
- Poorer perception of health
- More days of disability and greater service utilization
- Concurrent medical problem risk
Obese more likely to:
- Sleep less than 6 hours
- Experience at least one symptom of sleep disorder
- Think they have sleep problem
- Experience day time sleepiness
Cross-sectional data
Exposure and outcome measured at same time
Prospective data
Cohort studies; followed up over time
Biological mechanisms of sleep and obesity
Increased caloric intake:
- Increased hunger (more Ghrelin, less Leptin)
- Increased opportunity to eat
Reduced energy expenditure:
- Altered thermoregulation
- Increased fatigue
Commonly experienced sleep disorders by obese people
- Sleep disordered breathing: crowding; collapsed airway; compromised respiratory function
- Restless leg syndrome: hypofunction of dopamine system; diabetic neuropathy or cardiovascular pathology
Congenital insensitivity to pain
- Rare neurological disease
- Don’t feel extreme pain
- Frequent accidents and often die in childhood
Chronic vs. acute pain
Differs in terms of:
- Duration
- Pathology
- Biological value
- Prognosis
Impact of chronic pain
- 19% prevalence
- Smith et al. (2000): lower level of functioning and worse quality of life than those with HIV
- Accidental overdose
Insomnia and chronic pain
- Clinical studies: sleep is shallow, fragmented and unstable; addition of sleep disturbance worsen reports of symptoms
- Differences: increased N1, decreased SWS, shorter St2, more shift in stages, alpha intrusion in SWS, high cyclical alternative pattern, high sleep onset REM
- Experimental studies: sleep deprivation increased pain sensitivity and report, reduced central pain inhibitor responses, dampened mood and increased inflammation
Diffuse Noxious Inhibitory Control (DNIC)
- Conditioned pain modulation
- Tonic: cold pressor task
- Phasic: pressure pain threshold
- DNIC: % change in PPTh during cold pressure relative to baselines (increase indicates normal functioning)
- Sleep fragmentation reduces DNIC
Sleep restriction and inflammation (Haack et al., 2007)
Change in bodily discomfort and tiredness possibility related to IL-6 (plasma interleukin)
Temporal links between sleep and pain (Tang et al., 2012):
- Pain didn’t predict sleep quality- mood, cognitive arousal and physiological arousal did
- Sleep quality predicted pain next day for all day
- BUT high SQ = low pain in morning and high in the evening
Fibromyalgia (Mørk & Nilsen, 2011)
- Dose dependent association (risk increases according to frequency of sleep problems)
- Greater risk for women > 45 who reported sleep problems often or always
Does positive mood buffer problems sleeping? (Steptoe et al., 2008)
- Those with more sleep problems tend to acknowledge positive affect less
- Deeper sleep= eudaimonic wellbeing
- Association between psychological stress and sleep problems mediated by positive states
Sleep and daily mood (Totterdale et al., 1994)
- Associations are stronger and more consistent from sleep to mood than the other way
- Positive association between sleep quality and feeling cheerful, alert and involved next day
Acute sleep deprivation and psychopathology
In military (Kahn-Greene et al., 2007; Killgore et al., 2008): • Significant effect on somantic complaints, anxiety, depression and paranoia • Decrease in emotional intelligence
Sleep deprivation and emotional reactivity
- Sleep loss intensifies negative emotions and fatigue following daytime disruptive events
- Cognitive-energy model: sleep affects level of energy to self-regulate
Disrupted recognition of social cues/ emotions when sleep deprived (Van der Halm, 1996)
Sleep deprivation blunts ability to recognize emotion (particularly anger and happiness)
Impairment in emotional memory encoding when sleep deprived (Walker, 2012)
Less likely to remember positive words when sleep deprived
Possible neurological underpinnings in sleep deprivation and emotions (Yoo et al., 2007)
Sleep deprivation increased amygdala activation and decreased functional connectivity with medial prefrontal cortex
Sleep and depression
- Lower REM sleep latency, less SWS (particularly in first cycle), more awakenings, longer periods of awakenings
- 63% had significant sleep disturbances (hypersomnia or insomnia)
Sleep and bipolar
- Depression phase: REM dysregulation, less SWS, hypersomnia
- Mania/ hypomania: less need for sleep, delayed sleep onset, less REM latency, more REM intensity
- Inter-episodes: acute sleep deprivation can trigger a switch into mania; more sleep fragmentation and greater night-to-night variability
Sleep and anxiety
- Difficulty falling and staying asleep: more sleep onset latency, more frequent or lengthier awakenings, less total sleep time, less sleep efficiency
- Poor quality of sleep: restless and unsatisfying
Sleep and PTSD
- Hyperarousal
- Fragmented sleep, short sleep duration, motoric reactivity, REM short and rare
- Small-medium effect size for increased REM density, increased N1 and reduced SWS
How does pre-sleep stress affect sleep?
- Decreasing REM latency
- Increasing REM density and duration
- Increasing in arousal occurrence in sleep
Sleep and suicide
- Insomnia increases risk of completed suicide
- Time of suicide peaks in the morning
- 45.4% of participants who had committed suicide had recorded sleep disturbance
REM and mental health
- REM as abnormality marker
- Rem affects emotional memory processing
Sleep to forget sleep to remember model (SFSR)
Walker & Van der Helm
Remember:
• Theta oscillations: carriers to connect brain regions
• Acetylcholine: important long term consolidation and abundant in REM
Forget:
• Reduction in affective tone associated with recall (but information contained)
REM dreams
- Cartwright et al. (1984): divorcees that were not depressed had longer dreams, dealt with wider time frame and had dreams with themes of marital status
- Cartwright et al. (1998): significant reduction in POMS (profile of mood states) depression score overnight; especially females in non clinical sample
Clinical insomnia
Sleeping problem in own right and difficulties despite adequate opportunity (not just sleepiness)
Insomnia ICD-10
- 16 sleep disorder codes
- Organic or non-organic
- Largely irrelevant to psychology
Insomnia DSM-IV
- 2 categories: Primary and secondary
- Duration: 1 month
- Severity: Significantly impaired
- No frequency criterion
Insomnia DSM-5
- Removed secondary and primary
- Removed ‘non-restorative’
- Added ‘early morning awakening with inability to return to sleep’
- Frequency 3 nights/week
- Duration 3 months
- Specifications: 1. With non-sleep disorder mental comorbidity 2. With other medical comorbidity 3. With other sleep disorders
Insomnia ICSD-2
- 73 diagnoses
- Requires testing with PSG and expertise
- 11 subtypes: i.e. paradoxical, idiopathic
Insomnia ICSD-3
- Simplified
- Three: chronic, short term, other
- People with and without comorbidity
Convergence of DSM and ICSD for insomnia
- Elimination of other sleep disorders
- No primary or secondary categories
- Frequency, duration and severity
- Subjective complaint
- Daytime consequences and dissatisfaction with sleep
- ICSD allows for observers
Hard to differentiate insomniacs on objective measures
- Appearance
- TSD
- Daytime sleepiness
- Daytime functioning
Insomniacs and psychological characteristics
- MMPI links: hypochondriacs, depression, hysteria, psychopathic deviation, gender rigidity, social introversion
- Personality: neuroticism, internalisation, anxious concerns, perfectionism
Clinical interviews for insomnia
- Obtain: sleep history, overview of problems
- Info: nature of complaint, current sleep pattern, development course, impact of problem, treatment received
- Diet, substance use and medication; other psychiatric, medical or sleep problems
Narcolepsy
- 0.05% prevalence
- Excessive daytime sleepiness (sleep attacks)
- Disrupted night time sleep
- Could be due to a deficiency in orexin
Restless leg or periodic limb movement disorder
- 4.4% prevalence
- Lower extremities
- Disrupted night time sleep
Obstructive sleep apnea
- 2-4% prevalence
- Breathing effort
- Sleep disruption
Fatal familial insomnia
- Genetic degenerative brain disorder
- Pathogenic mutation of prion protein gene
- Unarousable coma and finally death (within 8-72 months after onset)
Factors when looking for causes for insomnia
- Predisposing: genes, biology, arousability
- Precipitating: noise, jet lag, life stresses
- Perpetuating (maintaining): cognitive, emotional, behavioural
Single factor theories for insomnia: Sleep hygiene
- Notion: lifestyle factors promote or inhibit sleep
* But no differences in sleep hygiene for good and poor sleepers
Single factor theories for insomnia: Stimulus Control Model
- Notion: sleep as a habit or conditioned behaviour (bed and bedroom is paired with non-sleeping behaviour for insomniacs)
- Good: bed > sleep > arousal reduction and sleep onset
Multiple factors of insomnia: Morin (1993) CBT model
- Dysfunctional cognitions
- Maladaptive habits
- Consequences
- Arousal
Multiple factors of insomnia: Harvey (2002) cognitive model
- Beliefs and safety behaviour
- Negative cognitive activity, arousal/distress, selective attention and monitoring, misperception of sleep/ daytime functioning
Multiple factors of insomnia: Lundh & Broman (2000) model
- Arousal: arousability, stimulus-arousal associations, CB strategies, interpersonal relations
- Appraisal: attributions, perfectionism, beliefs
Multiple factors of insomnia: Espie
- Attentional-intention-effort pathway
- Assumes that normal sleep is inhibited by explicit and implicit attention to sleep, intention to sleep, and direct and indirect attempts to control it
Hyperarousal in insomnia models
- This idea is embedded into many of the theories
- Insomnia often found in those with high (inappropriate) arousability
- Cognitive e.g. beliefs about sleep
- Behavioral e.g. poor stimulus control
Format of CBT for insomnia
- 4-12 weekly sessions
- Individual or group
- Self help book; telephone
CBT content and AASM recommendation
- Sleep hygiene education: none
- Relaxation training: high
- Biofeedback: moderate
- Imagery training: none
- Paradoxical intention: moderate
- Stimulus control therapy: high
- Sleep restriction: moderate
- Cognitive therapy: none
CBT pros and cons
Advantages: • Suitable for persistent insomnia • Patient’s preference • Gains maintained at follow-ups • Fewer and more tolerable side effects
Disadvantages:
• Not a panacea
• Longer treatment duration
• Limited access to treatment
Insomnia drug classes
- Barbituates
- Benzodiazepines
- Non-benzodiazepines
- Antidepressants
- Antihistamines
- Melatonin
- Herbal or dietary supplements
Drugs pros and cons
Advantages:
• Convenient (fast acting)
• Suitable for short term insomnia
Disadvantages: • Harsh side effects • Residual effects • Altered sleep architecture • Tolerance • Lethal overdose • Increased mortality and incidence of cancer • NICE recommends that non-medicine treatments should be considered and tried first
Alternative treatments
- Bright light therapy
- Exogenous melatonin
- Exercise
- Mindfulness
