1. REM Sleep (Paradoxical Sleep)

• Rate of Metabolism increases
• PR (Pulse Rate), BP (Blood Pressure), and O2 to Brain all increase
• Penile erection occurs - and this happens only during REM sleep (lasts ~15 min)
• This is physiologically normal and is used clinically to distinguish psychogenic from organic erectile dysfunction
• Total REM duration: ~8 hours per night (lifetime average across a full night)
  • Males: 6-7 hours of REM
  • Females: 7-8 hours of REM
• Dreams occur during REM - maximum dreaming happens here
• Recall of dreams is possible from REM sleep

2. NREM Sleep (Slow Wave Sleep)

• Occupies about 6.5 hours of a full night's sleep
• Associated with Somnambulism (Sleep Walking)
  • Admission/observation period for sleepwalking = 30 days
• NREM is restorative/deep sleep - the body repairs and grows during this phase

3. Brain Waves (States of Consciousness)

4. Forensic Psychiatry Note - Admission Period

• Admit = 30 days is written prominently
• This refers to the mandatory observation/admission period for psychiatric evaluation in medicolegal cases

5. Real vs. Fake Psychiatric Patient Comparison Table

REM vs. NREM Sleep - Complete Guide

Sleep Architecture: The Big Picture

NREM Sleep (Non-Rapid Eye Movement = Slow Wave Sleep)

What it is

NREM Stages

• As you enter sleep, EEG slows from alpha (8-12 Hz, awake/relaxed) -> theta (N1) -> spindles/K-complexes (N2) -> delta (N3)
• Cortical neurons fire in synchronized bursts - this is why EEG shows large, slow waves
• N3 = Slow Wave Sleep - this is the deepest, most restorative stage

NREM Physiology

• Heart rate slows and becomes regular
• Blood pressure decreases
• Sympathetic activity decreases; parasympathetic (vagal) tone increases
• Cerebral blood flow and brain metabolism markedly reduced

• Breathing is slow and regular
• Only the metabolic (automatic) respiratory system is active
• Muscle tone in upper airway decreases slightly
• Tidal volume decreases; CO2 rises mildly (2-8 mmHg), O2 drops slightly

• Body temperature falls - most of the nightly temperature decline occurs in NREM

• Growth Hormone (GH) is secreted maximally during N3 slow wave sleep - critical for tissue repair, muscle growth, and immunity

• Present but reduced

• Hard to wake someone from N3 - they are confused and disoriented if forcibly awakened (called "sleep inertia")

• Neuron firing rates decrease during NREM

Clinical conditions arising from NREM (specifically N3):

• Somnambulism (Sleepwalking) - arises from N3
• Night terrors - arise from N3
• Bedwetting (nocturnal enuresis) - occurs in N3
• These are called parasomnias of arousal because they occur when someone partially wakes from deep NREM

REM Sleep (Rapid Eye Movement = Paradoxical Sleep)

Why "Paradoxical"?

What happens in REM

• Desynchronized, low-voltage, fast - looks like the waking EEG
• Theta waves dominate
• Cortical neurons fire in non-synchronized bursts (like wakefulness)

• Rapid conjugate eye movements in all directions (more horizontal than vertical)
• Visible through closed eyelids - this is how it was first discovered by Aserinsky and Kleitman in 1953

• Atonia - nearly complete loss of muscle tone (the body is paralyzed)
• Only the diaphragm (breathing) and extraocular muscles retain activity
• This prevents you from physically acting out your dreams
• Small twitches in facial and finger/toe muscles still occur

• Tonic REM: parasympathetic tone increases further; heart rate and BP relatively stable
• Phasic REM: sympathetic bursts cause fluctuating heart rate, blood pressure, and respiration - pupil dilation/constriction alternates
• This is why heart attacks, angina, and strokes are more common in early morning (when REM is longest)

• Restored to waking levels during REM - the brain is metabolically as active as when awake

• Thermoregulation is suspended during REM - body temperature floats toward ambient temperature (like a poikilotherm)

• Irregular breathing
• Intercostal muscle tone is markedly suppressed
• Most dangerous period for respiratory compromise in sleep apnea, obesity, neuromuscular disease

• Occur exclusively during REM (the image notes state this)
• Clinically useful: if a man has erections during sleep (normal physiology), his erectile dysfunction when awake is likely psychogenic, not organic

• The most vivid, narrative, complex, emotional dreams occur in REM
• Dreams can be recalled if the person wakes during or just after REM
• Some dreaming (more passive) also occurs in NREM, but is less well-recalled

• Easy to wake from REM sleep (lighter sleep relative to N3)

• Young adults spend ~20-25% of total sleep in REM
• First REM bout: only 5-10 minutes
• REM bouts get longer as the night progresses - so most dreaming happens in the last 2-3 hours of sleep

Side-by-Side Comparison Table

The Sleep Cycle Across a Night

1. You fall asleep -> N1 -> N2 -> N3 (takes ~45-60 min)
2. You briefly ascend back to N1
3. First REM bout occurs (~5-10 min)
4. Repeat - each cycle ~90 min
5. With each cycle: N3 gets shorter, REM gets longer
6. By the last cycle: almost no N3; mostly N2 and long REM bouts

Key Memory Points (Exam Focus)

• REM = paradoxical because EEG is awake-like but person is asleep
• NREM N3 = slow wave because of high-voltage delta waves
• Sleepwalking, night terrors come from NREM N3 (not REM - common exam mistake)
• REM sleep behavior disorder = acting out dreams because atonia fails
• Penile erections only in REM - test for psychogenic vs. organic ED
• Growth hormone only in N3 - why children need deep sleep to grow
• Most dreaming recalled from REM - but dreaming occurs in both
• REM atonia protects you from acting out dreams; its failure = REM sleep behavior disorder (associated with Parkinson's disease and Lewy body dementia)