Stage 1 of Sleep
- Lightest sleep
- Easily awakened
- Lasts 10 minutes
- Occurs just once a night
- Amplitude increases
- Frequency decreases
Stage 2 of Sleep
- Light sleep, but deeper than stage 1
- Lasts 20 minutes
- Amplitude increases
- Frequency decreases
Stage 3 of Sleep
- Slow wave
- Deeper sleep than stage 2
- Start of large amplitude waves (delta waves)
- Less responsive to stimuli; hard to awaken
Stage 4 of Sleep
- Deepest sleep
- Delta waves
- Not paralyzed, just less mobile (sleepwalking and bed-wetting can occur)
- Decreased brain activity, but more synchronized
Electroencephalograph (EEG)
- Not a precise measurement of what is happening in a particular neuron
- Happens outside of the cell; electrodes are placed on the scalp
- Measures electrical potentials and averages of all neuronal activity
- Picks up average electrical signal that’s happening
- Finds specific patterns of firing in different stages of sleep
Amplitude
Largeness
Frequency
Rate
EEG of Awake and Alert Individual
• Beta waves (low amplitude, high frequency)
EEG of Drowsy Individual
• Alpha waves (low amplitude, lower frequency than beta; it is slowing down)
Rapid Eye Movement (REM) Sleep
- a.k.a. Paradoxical sleep
- EEG looks similar to when a person is awake (low amplitude, high frequency)
- Rapid eye movement
- Postural muscle paralysis
- Irregular heart rate, blood pressure and breathing rates
- Dreams with visual images and plots occur; very movie-like
Early Evening Sleep
• More of stages 3-4 and less REM
Late Evening Sleep
• More of REM and less of stages 3-4
REM Cycles
- Takes about 60-90 minutes from stages 1-4
- Cycle back from stage 4, to stage 3, to stage 2
- Instead cycling back to stage 1, one will go into REM sleep
- Cycle repeats all night
REM Behavior Disorder
- Very active during REM; not paralyzed
- Move around vigorously during REM and act out their dreams
- Dream about defending themselves against attack
- Can injure themselves and others
- Occurs mostly in older people
- Move around vigorously during REM, acting out dream. Dreams are often irrational, so actions would be irrational as well
- Multiple areas of damage in pons and midbrain
PGO Waves
- PGO: Pons, Geniculate, Occipital
* High-amplitude electrical potentials that occur in PGO order
Pons During Sleep
- Pons is activated first and turns on REM
- Pyramidal tract is involved and sends motor information
- Pons sends inhibitory messages down to the spinal cord and causes immobility
Lateral Geniculate Nucleus
- Located in the thalamus
* The visual part of the thalamus
Occipital Lobe (V2)
• Visual component of dreams
Delta Waves
- Large amplitude waves
* Loopy, big and slow
Norepinephrine, Serotonin, Histamine and Orexin
- Increased wakefulness
- Decreased slow wave sleep
- Decreased REM
Histamine
- Antihistamines block receptors
* Nondrowsy antihistamines don’t cross blood-brain barrier
Orexin
- Produced by neurons in the hypothalamus
* Turns on eating
Acetylcholine and Sleep
- Increased wakefulness
- Decreased slow wave sleep
- Increased REM
GABA and Sleep
- Decreased wakefulness
- Increased slow wave sleep
- Increased REM
Adenosine
- Produced by metabolic activity in cells; the more active the cells are, the more adenosine is made
- Builds up during the day
- High levels of it turn on sleep and is decreased by acetylcholine
- During sleep, levels decrease because there is less cell activity during sleep
- Caffeine blocks adenosine receptors and sleep does not get turned on
Melatonin
- Hormone; endocrine system
- Pineal gland, between thalamus and midbrain
- Natural rhythm; melatonin released 2-3 hours prior to normal bedtime
- Turns on sleep
- Helps adjust to new time zones
Effects of Melatonin
• Longterm use in lab animals known to cause: - Impaired learning - Impaired fertility - Impaired fetal development • Unknown longterm effects in humans
Sleeping Pills
- Turn off wakefulness
- Norepinephrine antagonist
- Not getting the right sleep in the amounts you need after becoming dependent
Newer Generation Sleeping Pills
- Turns on sleep
- GABA agonist
- Bizarre side effects occur during sleep and while awake; may not be able to control impulses, could develop gambling problems
- Ambien, Lunesta
Rozarem
- Melatonin agonist
- Prescribed
- Good if the person has a hard time initially getting to sleep
Night Terrors
- Not to be confused with nightmares.
- Occurs during NREM sleep, common in children. Not associated with dreams. Child wakes up screaming.
- Nightmares occur during REM, the child can usually describe it.
- Children often grow out of it.
Fatal Familial Insomnia
- Rare genetic disorder
- Onset usually in middle age
- Death follows within 2-3 years
- Damage to thalamus
Fatal Familial Insomnia Symptoms
- Starts with bouts of insomnia and cognitive disturbances
- Confusion, slowed cognitive processes, memory deficits much more pronounced with this group of people
- Hallucinations
- Extreme weight loss
- Complete lack of sleep
- Dementia and then death
Stages of Metabolism
- Absorptive Phase (when we are eating)
* Fasting Phase (when we are not eating)
Absorptive Phase
- Occurs during and just after eating
* Carbs are broken down into glucose
Glucose
• Primary source of fuel in the brain and spinal cord
Storing Carbs in the Absorptive Phase
- Insulin released by pancreas.
- Glucose enters cells and is used as fuel.
- Some excess converted to glycogen by liver. Remaining excess converted to triglycerides and stored as fat.
- Proteins broken down to amino acids and used for protein synthesis. Excess converted to triglycerides and stored as fat.
- Fats remain as fat. It is not used as fuel in absorptive phase. Immediately converted to triglycerides and stored.
Fasting Phase
- Nutrients are not immediately available from digestive system
- Fuel comes from short term and long term reserves
Short Term Reserve
- Glycogen in liver converted back to glucose
- 300 calories of glucose stored in liver
- Supplies Central Nervous System
Long Term Reserve
- Adipose tissue
- Triglycerides broken down into fatty acids and glycerol
- Glycerol converted by liver into glucose for central nervous system
Triglycerides
• Fatty acids used by body cells.