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Sleep What is normal?

Explore the basics of normal sleep, including stages like REM and SWS, how it is measured, common sleep disorders like insomnia and narcolepsy, and the impacts of sleep apnoea and circadian rhythm disorders. Learn about the relationship between insomnia and depression.

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Sleep What is normal?

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  1. SleepWhat is normal? Dr Andrew Mayers amayers@bournemouth.ac.uk

  2. Sleep • Overview • Normal sleep • How much should we get? • Sleep disorders • Insomnia and hypersomnia • Narcolepsy • Sleep Apnoea • Circadian rhythm disorders • Poor sleep and depression

  3. 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

  4. 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

  5. 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

  6. Normal sleep (EEG)

  7. 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

  8. 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)

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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)

  14. 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)

  15. 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

  16. Sleep EEG • Sleep EEG in healthy person Sleep EEG in depressed pt

  17. 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

  18. 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)

  19. 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 • Catastrophisethe impact (Harvey 2003) • Daytime function • Work performance • Social relationships • This serves to exacerbate the sleep problem • Self-fulfilling prophecy

  20. 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

  21. 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)

  22. 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 byMayers & 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

  23. 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

  24. 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

  25. 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

  26. 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)

  27. 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)

  28. 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

  29. 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

  30. 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.

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