Post on 19-Jan-2016
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Sleep
What is normal?
Dr Andrew Mayers
amayers@bournemouth.ac.uk
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Sleep
Overview Normal sleep
How much should we get? Sleep disorders
Insomnia and hypersomnia Narcolepsy Sleep Apnoea Circadian rhythm disorders
Poor sleep and depression
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An overview of normal sleep
What is normal sleep? Average sleep 6½ - 8 hours each night
Regulated by 25-hour circadian rhythm Adjusted to coincide with normal wake-sleep
routines Use cues from environment
Clocks and sunlight/darkness (Thase, 1998)
Much of what we learn here can be read in my review (Mayers & Baldwin, 2006)
But, before we see what is measured… We should understand how sleep is measured
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Normal sleep
Sleep EEG stages (Rechtschaffen and Kales, 1968)
Stage 1 – light sleep Similar to alert wakefulness 2-5% of ‘healthy’ sleep episode
Stage 2 – getting deeper… About 55% of sleep episode
Stages 3 and 4 usually examined together Often referred to as slow-wave sleep (SWS)
About 13-25% of sleep episode
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Normal sleep
Sleep EEG stages Sleep usually divided into 4 to 6 cyclic progressions SWS
Predominates in early sleep episode Rapid-eye-movement (REM) sleep
Appears after 1st cycle Periods of intense brain activity Frequent and intense bursts of eye movement
But with lack of muscle tone elsewhere First REM period usually occurs after 60-110 minutes REM sleep periods get longer and denser across
night
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Normal sleep (EEG)
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REM sleep vs. SWS
SWS associated with human growth hormone (GH) If SWS reduced, then so is GH (Van Cauter & Copinschi,
1999)
Low GH may be associated poor quality of life SWS probably associated physical restoration
REM sleep commonly associated with dreaming Dreams can often reflect current thinking styles and
mood REM sleep often seen as psychological ‘filing system’ Depression associated with REM/SWS disruption
SWS REM (Benca, 2001)
Most antidepressants suppress REM sleep We will discuss this later
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Sleep: where does it go wrong?
We will now look at examples of sleep disorders Not enough time to review them all
But we will explore some of most common ones Many of the sleep disorders relate to sleep stage
disruption While others relate to unusual occurrences during sleep
Sleep disorders categorised according to nature Dyssomnias
Sleep timing, stage disruption and sleep quality Parasomnias
Physical and behavioural abnormalities during sleep We will not look at that today (but do ask if you
want to know more)
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Insomnia
Most common sleep disorder Problems initiating sleep (early insomnia) Maintaining sleep (middle insomnia) Or early morning awakening (late insomnia)
At least 2 weeks (nearly every day) for 1 month or more
Phillippa will look at this in more depth later Can lead to significant problems
Physical health Impairment in normal functioning…
Chris will explore this Mental health – especially depression
I will discuss this further
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Narcolepsy
Features (Overeem, et al. 2001) Excessive daytime sleepiness (EDS)
May be as mild as subjective feelings of sleepiness Or as extreme as sudden irresistible sleep attacks
Hypnagogic hallucinations Often frightening images that occur at sleep onset
Usually visual, but can be auditory Cataplexy
Sudden collapsing and total muscle tone loss Most often in association with intense emotion
Usually laughter or excitement Sleep paralysis
Narcoleptics go straight into REM sleep
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Sleep apnoea
Obstructive sleep apnoea (OSA) Patients briefly stop breathing during sleep
Similar to choking Causes brief arousals
Followed by ‘snoring’ Patient (normally) returns to normal breathing
Little physical damage as a result Central sleep apnoea (CSA)
More rare, but potentially more damaging Breathing stops for long periods May even cause death
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Sleep apnoea
Consequences Sleep disruption
Poor concentration, car accidents, etc High blood pressure
Breathing stops frequently during the night Increased stress on the heart Heart has to work harder Increases blood pressure
Among OSA pts without high blood pressure 45% will develop this within 4 years
Among patients with the highest blood pressure 80% have OSA
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Circadian rhythm sleep disorders (CRSD)
Misalignment of patient’s sleep patterns and ‘societal norm’
Sleep occurs at wrong time of day
Or ‘out of phase’
CRSD sleep disorders:
Jet lag
Shift work
Sleep phase syndromes
CRSD associated with other circadian rhythm-related factors Melatonin release and body temperature (Dagan, 2002)
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Relationship between insomnia and depression
One-third of patients with chronic sleep problems present mood disorders
Most patients with mood disorders experience insomnia And, less often, hypersomnia (Benca, et al. 1997)
Poor sleep implicated in most psychiatric disorders
But more pervasive and consistent in depression
Sleep disturbance common in suicidal patients Subjective sleep quality poorer in suicidal depressed pts
(Singareddy & Balon, 2001)
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Insomnia and depression
Sleep EEG analyses (Benca, et al. 1997)
Depressed patients show:
Shorter total sleep time
Longer sleep latency
Less slow-wave sleep
Shorter REM latency
Greater REM density
Compared to controls
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Sleep EEG
Sleep EEG in healthy person Sleep EEG in depressed pt
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Insomnia may predict depression
Longitudinal study (Ford and Kamerow, 1989) Insomnia and depression measured at baseline/1 year
follow up If insomnia present at both time points
Risk of developing depression 40x greater Than if no insomnia present
If insomnia resolved by follow up Risk of developing depression 2x greater
Another seminal study (Breslau et al. 1996) Similar to Ford & Kamerow, but 3.5 year follow-up If history insomnia at baseline
Risk of developing first depression by follow-up 15.9% No history of insomnia at baseline, risk = 4.6%
4x more likely to develop ‘new’ depression 3x more likely with history hypersomnia
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Sleep perceptions in insomnia and depression
Differences in sleep perception between insomnia and depression Longitudinal studies focus on diagnoses
Also tend to use objective measures – sleep EEG But sleep perceptions also important
These may differ between insomnia and depression Insomnia may be related to anxiety
Cognitive bias focus on perceptions of sleep timing (Harvey 2000, 2002, 2003)
Depression related to perceptions of sleep satisfaction (Mayers, et al., 2003; Mayers & Baldwin, 2006)
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Insomnia and anxiety
Faulty sleep cognition implicated in insomnia (Harvey 2002,
2003)
Worry about poor sleep may maintain insomnia Pre-sleep cognitive activity associated negative
thoughts
Intensifies worry, especially about getting to sleep Catastrophise the impact (Harvey 2003)
Daytime function Work performance Social relationships
This serves to exacerbate the sleep problem Self-fulfilling prophecy
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Sleep perceptions and depression
Sleep cognitions also implicated in depression But tend to reflect negative thoughts (Beck 1987)
Negativity may explain sleep perception inaccuracy in depression (Argyropoulos 2003)
We will see more about that shortly Additional REM activity may be partial explanation
(Johnson 2005)
Particularly as result of dreaming Reduced rationality Negative content and emotion
Sleep satisfaction may be more relevant in depression
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Sleep perceptions and depression
Subjective sleep satisfaction measured in depressed populations In one study
Depressed pts reported sig poorer satisfaction than controls
Even though sleep timing perceptions were similar between groups (Mayers, et al 2003)
In a later study Variance in sleep timing perceptions was more likely
to be explained by anxiety And sleep satisfaction perceptions were more
likely to be explained by depression (Mayers, et al 2009)
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Effect of antidepressants on sleep
Antidepressants may help mood… But they may also have an effect on sleep
The clinician must consider this when treating In a review by Mayers & Baldwin (2005) effects were
examined across all types of antidepressant Tricyclics (TCAs): e.g. amitriptyline
Often associated with sedation Selective Serotonin Reuptake Inhibitors (SSRIs): e.g.
Prozac Frequently linked to insomnia BUT supress REM sleep (more so than TCAs)
Useful for narcolepsy Some newer meds (e.g. mirtazapine) similar to TCAs
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Sleep disorders and depression
Narcolepsy Several studies indicate relationship with mental well
being Narcoleptic pts demonstrated several problems:
Sig poorer quality of life perceptions vs. controls Narcoleptic pts more likely to have mental illness (OR:
4.06) Including depression
EDS may explain depression in narcolepsy – sheer fatigue Narcolepsy associated with REM sleep abnormalities Cataplexy often treated with antidepressants:
Suppress REM sleep … improve mood Reduces cataplexy, sleep paralysis and hypnagogic
hallucinations
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Sleep disorders and depression
Obstructive sleep apnoea (OSA; Andrews & Oei 2004) Several studies indicate relationship with mental well
being OSA pts showed more evidence of dep than controls
Depression in OSA may be secondary Effect disappears when controlling for other factors
OSA associated with frequent arousals from sleep This has impact on EDS leads to depression?
OSA associated with increases in Stage 1 sleep Usually at the expense of SWS Pt may not feel refreshed upon waking
So depression may be related to sleep satisfaction
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Sleep disorders and depression
Circadian rhythm sleep disorders (CRSD)
CRSD may be associated with EDS
Which may be related to poor mood
But also linked with melatonin Melatonin levels reduced in depression (Brown, 1985)
Depletion also observed in CRSD (Shibui et al 1999)
We will now see how this relates to CRSD types
Jet lag, shift work and delayed sleep phase syndromes
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Jet lag and depression
Melatonin may be involved in triggering sleep Via complex relationship with serotonin
We know that serotonin is strongly linked with depression (Idzikowski 1991)
Jet lag is linked with melatonin reduction Jet lag associated with:
Fatigue, sleep schedule disturbance, impaired cognitive functions, and depression
More so with east-bound flights Over 5 or more time zones
However, more likely to be related to relapse Than new depression
Jet lag may exacerbate, rather than cause, depression (Katz et al 2002)
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Shift work and depression
Regular shift workers appear to be more prone to depression Shift workers present several problems (Sasaki &
Takahashi 1990): Insomnia, autonomic dysfunction, physical
complaints, and depression Shift workers show more problems than day workers
(Drake et al 2004): EDS, insomnia, absenteeism, accidents and
depression Females sig more prone to these effects than males
Depression (measured by BDI) worse for shift workers Than traditional workers (Goodrich & Weaver 1998)
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Sleep phase syndromes and depression
Advanced sleep phase syndrome (ASPS) is typical in older people
Earlier to bed; early morning awakening
Delayed sleep phase syndrome (DSPS) is typical in younger people
Later sleep onset times; late morning waking ASPS has been associated with depression (Schrader et al
1996)
But DSPS receives most attention in the literature (Regestein & Monk 1995)
Three-quarters of DSPS pts had history of depression
For 50% of these, depression is resistant to treatment
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Summary
Relationship between sleep disorders and MI mixed Considerable evidence with insomnia and hypersomnia
Poorer sleep length and disturbance Problems relating to sleep architecture
REM sleep vs. SWS Although insomnia may be more related to anxiety
Particularly in respect of reports of sleep timing Depression more likely to be related to sleep
satisfaction Antidepressants have marked effect on sleep
Whether positive or negative depends on type
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Summary
Strong links between narcolepsy and depression Particularly through EDS and cataplexy Treatments for narcolepsy often relieve depression
Relationship with sleep apnoea less clear Depression in OSA may be secondary Although sleep satisfaction may be poorer in OSA
Depression found in other dyssomnias Circadian rhythm disorders, jet lag, etc.