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Sleep + Circadian Rhythms - Coggle Diagram
Sleep + Circadian Rhythms
Brain States
Awake😁
Brain is very active
REM (rapid eye movement) sleep🦄
Brain is very active
Some parts are more active than when awake
🔥Not processing sensory info❌
Dreaming occurs💭
AKA "Hallucinating brain"
Skeletal muscles == paralyzed💪
Everything except eyes + breathing organs
NREM sleep😴
Brain is resting
Divided into 3 stages
Stage 1 / N1
Stage 2 / N2
Stage 3 / N3
More NREM sleep == more restful feeling when waking up
Low metabolic rate
Low rate of AP's firing
Electroencephalogram (EEG)
Records brain's overall brain activity ⚡️
Cannot pick deeper electrical signals happening within the brain
Small electrical current around dendrites of cerebral cortex
Caused by ion movement
Detects small current happening under skull and meninges 💀
Recording activity of lots of neurons
Can distinguish btwn different sleep states
Awake😁
High frequency + low amplitude pattern
Stage 1 / N1😴
High frequency + low amplitude pattern
Stage 2 / N2😴
Medium frequency + amplitude pattern
Stage 3 / N3😴
Low frequency + high amplitude pattern
Nonsense activity🤪
REM🦄
High frequency + low amplitude pattern
Sleep Cycles
Going to sleep🌅
Awake
REM
N1
N2
N3
1st half
Alternating from N1 + N3
Deep sleep 😴
2nd half
Alternating from REM + N2
Dreaming🦄
Sleep deprivation
More REM sleep🦄
AKA REM rebound
Neural Mechanisms of Sleep
Sleep regulation occurring in neurons found in brain stem + basal forebrain
Different sleep states
Caused by clusters of neurons activating + inhibiting each other
Neurons going down spinal cord⬇️
🥶Paralyze skeletal muscles💪
Neurotransmitters in different states
Awake😁
High levels of monoamines
Serotonin
Norepinephrine
Histamine
Acetlycholine
in Basal forebrain
Orexin (Hypocretin)
NREM🦄
High levels of GABA
Adenosine
Serotonin
Norepinephrine
Reduced activity compared to when awake
REM 😴
High levels of Acetlychloine
in midbrain / pons
Alternating activity of REM-on neurons (acetylcholine from midbrain / pons) + REM-off neuron (serotonin + norepinephrine)
Switch brain btwn REM + NREM sleep
Towards end of REM-episode
Increased REM-off activity
Inhibits / decreases REM-on activity
Switches from REM to NREM
NREM episode
Increased REM-on activity
Inhibits / decreases REM-off activity
Switches from NREM to REM
State Comparision
Awake
High levels of monoamines + acetylcholine
NREM
High levels of GABA + medium level of monoamines
REM
High level of acetylcholine
Orexin / Hypocretin
Peptide neurotransmitter
Linked to appetite🍔
⬆️Promotes wakefulness😁
Narcolepsy
Autoimmune disorder where someone spontaneously falls asleep
Can be triggered by strong emotions🤩
In canines
Genetic disorder
Receptors mutated so it doesn't proper effect
Grelin = lets you know that you're hungry
Orexin == Greek word for appetite
Hypocretin
Found in hypothalamus + similar to cretin
Sleep Medications
💊
Acting on GABA(a) receptors
Inhibitory
Involved in NREM but not associated w/ insomnia
Awake-promoting systems too active, but GABA is not involved
Benzodiazepines
Ex. Ativan + Valium
Additive effect of benzo + alcohol
Too much inhibition
Fatal💀
Not used as much b/c addictive + unsafe⚠️
Z-Drugs
Ex. Ambien + Sonata + Lunesta
Bind to benzodiazepine binding site, but not chemically the same
Still has same effect
Slightly more selective
Only bind to some GABA(a) receptors
Don't inhibit breathing as much
Acting on other neurotransmitters
Orexin antagonists
Ex. Belsomra
Inhibits effect of orexin🛡
Keeps you awake🏃♀️
Melatonin agonists
Ex. Rozerem + melatonin
Promotes sleep🥱
Antihistamines
Ex. Benadryl + Tylenol pain meds
Inhibits histamine system
Brain gets used to them🧠
Adapts
No longer have an effect after 2-3 nights
Target awake-promoting systems
Non-drug Treatment for Insomnia == Cognitive Behavioral Therapy (CBT-I)
Results in more time spent in deep sleep + less time awake😴
Has longer lasting effects than drug treatments
Glymphatic System
Cleans brain during sleep🛁
Subarachnoid space
Where CSF stays during awake state
Space around artery
Space around vein
Lymphatic system
Brain == highly metabolically active
Creates many byproducts / wastes / toxins🤮
Cannot clean while awake b/c not compatible
CSF penetrates deeper + filters through tissue
"G" == glia
Astrocytes function similarly to lymphatic system (for rest of body)
Another sleep theory🤔
Memory Consolidation
Store short-term memory into long-term memory
Control of Sleep
Controlled by combined effects of homeostatic + circadian processes🥞
Homeostatic sleep drive
Longer you've been awake == more pressure to sleep
Mediated by adenosine
Builds up as ATP is broken down while awake🥞
Rinsed out by glymphatic system💦
Neuromodulator
Inhibits ACh neurons in basal forebrain🛡
Caffeine☕️
Similar enough to be able to bind to receptors👯♀️
Just blocks, not inhibits🛡
Competes w/ adenosine while awake
Long-term usage👵🏻
More adenosine receptors
☕️Feel like you need more caffeine to feel effect☕️
Can be reversed by detox🔄
Circadian System
24hrs cycle🏪