Transcript A Good Brain Anatomy Site:

Sleep and Sleep Histories
Douglas Moul, M.D., M.P.H.
?
“Consciousness is consciousness of an object.”
-- Jean-Paul Sartre
Death = Sleep ?
To be or not to be, that is the question-- whether
it is more noble in the mind to suffer the slings
and arrows of outrageous fortune, or to take
arms against a sea of troubles, and by opposing,
end them -To die..., to sleep..., perchance to dream…
-- Hamlet
Modes of Sentience
• Wakefulness
• Slow Wave Sleep
• Rapid Eye-Movement Sleep
Modes of Insentience
• Coma
• Death
Hallucinations and Dreams
• Both often occur in the absence of a
consensually validated stimulus.
• Both are experienced perceptually.
• Both can dominate awareness
• Both can be pleasant or unpleasant
• Both can at times cause overt behavior
Hallucinations vs.
• Usually during
wakefulness
• Auditory > Visual
• Not volitionally guided
• Interferes with the stream
of thought
• Usually not built from
ordinary daily events
Dreams
• Usually during REM
sleep
• Visual > Auditory
• “Lucid” Dreams can be
thematically guided
• When experienced, is the
stream of thought
• Often contain “day
residues.”
Myths about Sleep and Dreams
• If a person doesn’t get sleep, he or she will
become psychotic.
• Everyone must get 7.5 hours of sleep.
• Psychiatrists are taught how to interpret dreams
properly.
• Nightmares and hypnopompic/hypnogogic
hallucinations are abnormal.
• Sleep apneas are always abnormal.
A Good Brain Anatomy Site:
http://pegasus.cc.ucf.edu/~Brainmd1/brain.html#table
Stage I Sleep: Going to Sleep
• Usually requires state of lowered autonomic
arousal
• Transition from alpha to theta waves on EEG
• Is a light sleep, easily responsive to sounds
• Typically lasts from 1 to 7 minutes
• Hypnic Myoclonus may occur
Stage II Sleep: The Thalamus’ Reticular
Nucleus’ Sleep Spindles
•
•
•
•
•
Sleep Spindles and K complexes
Bodily movements continue
Lasts usually 10-25 minutes during first cycle
Constitutes 45-55% of sleep
Probably initiates 0.5o F temperature reduction
through the Hypothalamus
Stages III-IV: Deep Sleep
• High voltage Delta waves now predominate in
EEG
• High stimulus thresholds normally for arousal.
• Psychologically probably the stage that tells a
person he has slept.
• Skeletal muscles still active!
REM Sleep
•
•
•
•
Usually is an arousal from Delta sleep
Desynchrony in the EEG
PGO waves from Pons to Thalamus to Cortex
Theta waves in Septum and Hippocampus (related
to memory/dream function?)
• Pontine reticular formation activation with skeletal
muscle atonia and poikilothermia
• Lowered cardiac and pulmonary rhythms
• Periodic penile and clitoral tumescence
Wakefulness
• Greater tendency to arouse from REM (REM
propensity is circadian; SWS propensity is about
length-of-wakefulness)
• Septal and Hippocampal Theta waves occur
during wakefulness !
• With apneas, brief awake spells can be forgotten
• Sleepiness and Fatigue can be different
symptoms.
Breathing During Sleep
• Sleep onset resets chemical sensitivity to PO2 and
PCO2
• In moving to new setpoints, apneas may occur,
and are fairly normal
• PCO2 usually the critical setpoint for breathing
during sleep
• Decreased pharyngeal tone: snoring and
obstructive sleep apnea
• Greater irregularity during REM sleep
Prominent Nocturnal Hormone
Patterns
• Cortisol starts out decreasing, reaches a daily
minimum, then rises to a daily maximum about
dawn.
• 80% of Growth Hormone can occur in the first
Delta sleep period.
• Melatonin is entrained to the circadian and
seasonal rhythms if not directly suppressed by
bright light.
Three Physiological Factors regarding
Sleep Propensity
• Previous Sleep Debt
• State of Autonomic Arousal
• Circadian Time
Effects of Sleep Deprivation
Not so Good
• Decreased sleep latency
• Risk of microsleeps
• Lowered intellectual
performance and creativity
• Irritability
• Decreased vigilance
• Danger of switches to Mania in
Bipolar patients
Good
• Temporarily
decreased
depressive
mood in some
depressed
patients
Factual Pearls concerning Sleep
• There is a 90-minute NonREM-REM Cycle of
sleep stages across the night
• Circadian maturity only begins to appear by 6
weeks post-partum, and may take months; Infants
have a lot of REM sleep.
• Women as a group have better sleep architecture,
but lower sleep quality than men.
• The elderly may not have any Delta sleep and
generally have lighter sleep
Effects of Alcohol
• Alcohol (affects GABA & other receptors )
induces sleep, decreases pharyngeal muscle tone
encouraging obstructive sleep apneas, and
initially depresses REM; later in the night REM
rebounds, with possible nightmares and/or
awakening.
• Sober alcoholics can expect to have poorer sleep
architecture and sleep satisfaction for over a year
after they have stopped drinking.
Effects of Other Layman Drugs
• Caffeine antagonizes Adenosine, a neuromodulator
that decreases secretion of autonomically active
chemicals (DA, NE,etc.)
• H1 Antihistamines antagonize Histamine, an
activating neurochemical during wakefulness
• Nicotine is a cholinergic stimulant.
• Drugs with Anticholinergic properties may help with
sleep, but impair daytime memory
Effects of Common Medications
• Benzodiazepines (e.g. Valium) (affect GABA)
tend to suppress SWS
• Antidepressants and MAOIs tend to suppress
REM Sleep
• Stimulants usually act on Dopamine or
Norepinephrine and suppress all stages.
• Many medications hit multiple receptors, and
their effects on sleep can be dose-dependent and
somewhat unpredictable.