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.