Sleep
Functions of Sleep
Restorative/recuperation is the replenishment of depleted resources used during the day.
Information processing is important for consolidating memories, and memories are improved by sleep.
Evolutionary theory/The adaptive hypothesis holds the premises that:
Animals that need more time to get food overall sleep less.
That when predators are removed, animals can hide and sleep more.
And that more vulnerable animals sleep little.
Polysomnography
Studies that focus on sleep and sleep disorders.
Takes measures of the following:
Heart rate.
Breathing.
Brain waves (With an EGG.).
Eye movements (With an EOG.)
Muscle activity (With an EMG.)
Circadian Rhythms
Circadian rhythm is the name given to our biological clocks. It serves as a consistent cycle of our bodily activity as well as behaviors that occur during a twenty-four-hour period.
The term “Circadian” means “about a day.”
Circadian rhythms are physical, mental, and behavioral changes that follow a roughly 24-hour cycle and respond primarily to light and darkness in an organism's environment.
Low points in the Circadian rhythms cycle are between 1-4 Pm and 2-4 Pm.
Key ways we can upset our circadian rhythms include:
Shift work
Jet lag
Weekends
Suprachiasmatic Nucleus
The suprachiasmatic Nucleus (SCN) is the area in the hypothalamus that is just above the optic chiasm.
The SCN regulates the pineal gland’s secretion of melatonin.
Pineal Gland
The pineal gland plays an important role in the circadian rhythm as well as our sleep and wake cycles.
The pineal gland releases melatonin which affects sleep.
Levels of melatonin change within a twenty-four-hour cycle.
Melatonin both reduces jet lag and is used as a sleep aid.
Types of Sleep
There are two types of sleep, which include REM and NREM.
It was thought that there were four stages of NREM; however, sleep researcher no longer differentiates between stages three and four, so there is officially 3 stages of NREM.
Sequence of Stages
The REM stage gets progressively longer during the night
Deep NREM gets progressively shorter
More deep NREM in the first half of the night
More REM in the second part of the night
Sleeping only 4 hours instead of the usual 7 results in losing more REM sleep
NREM: Non-Rem
NREM sleep starts with Stage 1
Stages 1 and 2 are considered light sleep or light NREM
Stage 1 is so light that a person might not even realize they were asleep
In Stage 1, a person can be easily awakened by their partner, but they may insist that they haven't been sleeping
Stage 3 is considered deep sleep or deep NREM. Stage 3 is also known as delta sleep or slow wave sleep; It is very difficult to awaken a person in Stage 3.
NREM
Bedwetting: frequently happens during deep sleep.
Night terrors: prevalent among children.
Sleepwalking: takes place during NREM as there is partial paralysis during REM, preventing walking.
Sleep Disorders
Sleepwalking occurs during non-rapid eye movement (NREM) sleep.
The person gets up and walks around during sleepwalking.
The person is not acting out their dreams during sleepwalking.
Sleepwalking can be dangerous as the person may walk out of a second-floor window.
There is a controversial defense in crimes committed by sleepwalkers, also known as "Sleepy Murderers."
A sleep-related eating disorder is a condition where a person eats while sleepwalking.
Night Terrors
Happen during NREM sleep.
A person sits up in bed, looks terrified, and screams.
Usually, no memory of the experience in the morning.
Nightmares
Happen during REM sleep.
A person may see frightening images and wake up.
Upon awakening, a person can describe the nightmare in great detail.
Rem
REM stands for Rapid Eye Movement and is characterized by rapid eye movement.
Approximately 20-25% of the night is spent in REM.
A person goes into REM 4 or 5 times per night.
The REM stage comes approximately every 90 minutes.
The REM stage gets progressively longer throughout the night.
REM is also called Paradoxical sleep because brain waves look like those of an awake person or a person in light sleep, but it is hard to awaken the person.
REM is considered active sleep because bodily functions speed up.
REM: Partial Paralysis
Fibers from the brain, including pons, descend and inhibit motor neurons during REM sleep, causing sleep paralysis.
Jouvet, a researcher, cut fibers in cats during REM sleep.
The cats "acted out" their dreams, indicating that the paralysis during REM is necessary to prevent physical movement during dreams.
Sleepwalking does not occur during REM sleep because of partial paralysis.
REM & Dreams
Dreaming mostly occurs during REM sleep.
Non-REM sleep involves less vivid dreams that are more like thinking.
Everyone dreams, but not everyone remembers their dreams.
The amount of REM sleep decreases with age.
REM sleep is important for neural development and memory consolidation.
A night of sleep with REM deprivation leads to less retention of information.
NREM sleep is also involved in memory.
Dreams can incorporate external and internal stimuli.
No sleep learning occurs, meaning you can't learn a language by playing tapes while asleep.
REM Rebound
REM Rebound:
Increase in REM to make up for a deficit
Happens after REM deprivation
Recovery night allows for sleeping through the night
Drugs that decrease REM can cause REM rebound:
Happens when discontinued
REM rebound can come in the form of nightmares.
Sleep Disorders: Insomnia
Difficulty falling asleep and staying asleep.
Stress and anxiety are major causes of insomnia.
Depression can cause early morning awakening despite being able to fall asleep.
Sleeping pills such as tranquilizers, barbiturates, and alcohol can induce insomnia.
Drug-Induced Insomnia
Tranquilizers, Barbiturates, and Alcohol can interfere with REM and overall sleep quality.
Over time, the body can build up a tolerance to these substances, leading to a decrease in sleep quality.
When someone quits taking these substances, they may experience insomnia.
Once they do fall asleep, they may experience REM rebound in the form of nightmares.
Sleep Deprivation: Microsleeps
Microsleeps occur when a person has been sleep deprived.
Microsleeps are fleeting, uncontrollable, brief episodes of sleep that last for seconds.
Microsleeps are sometimes referred to as "zoning out."
During microsleeps, the brainwaves resemble those of sleep.
Microsleeps can be dangerous, especially when driving or operating heavy machinery.
Sleep Disorders: Apnea
Sleep Apnea is a condition where a person stops breathing for minutes at a time, and this can happen many times during the night.
Sleep Apnea increases the risk of heart attacks and other health problems.
Anoxia, which is a lack of oxygen to the brain, can occur due to Sleep Apnea.
Sleep Apnea is sometimes referred to as Sudden Adult Death Syndrome (SADS) because it can be dangerous to stop breathing many times per night.
People with Sleep Apnea are often loud snorers.
The treatment for Sleep Apnea is a CPAP machine.
Sleep Apnea Remedies
Losing weight
Stop smoking
Reduce sleeping pill use
Dental implants
CPAP machine: Continuous positive airway pressure
Sleep Disorders: Narcolepsy
Narcolepsy Symptoms
Sleep attacks & excessive daytime sleepiness triggered by emotions such as anger or laughter
Cataplexy: temporary loss of muscle tone causing falls while awake
Sleep paralysis: inability to move after waking up
Hypnagogic hallucinations: upsetting hallucinations while falling asleep or waking up
Testing for Narcolepsy
In a sleep lab, individuals with narcolepsy go straight into REM stage instead of going through NREM first.
Disorders: REM Sleep Behavior Disorder
People with this disorder lack the normal muscle paralysis that occurs during REM sleep.
As a result, they act out their dreams while sleeping.
This disorder is more common in older males.
It can be dangerous as there is a risk of physical injury to oneself or to the person sharing the bed.
Sleep Promoting Drugs
Benzodiazepines
Benzodiazepines are GABA agonists that increase GABA.
Diazepam (Valium) is a benzodiazepine.
Benzodiazepines can be addictive and cause an overdose when combined with alcohol and opiates by suppressing breathing.
Z-Drugs
Z-drugs are similar to benzodiazepines and also GABA agonists.
Ambien is a Z-drug that can cause sleep disturbances like sleepwalking or sleep eating.
Sleep Hygiene
Avoid full-spectrum light (phones, TV) before going to sleep
Exercise is good for sleep, but not right before bedtime
Avoid caffeine or other stimulants
Establish a regular sleep schedule to regulate circadian rhythms
Avoid eating before sleeping, especially spicy foods
Get exposure to natural light in the morning to help with circadian rhythms
Reduce stress.
Parts of the Brain
Pons: pathways that cause partial paralysis during REM by inhibiting motor neurons
Raphe Nucleus: main area of serotonergic pathways that promote sleep
Serotonin is responsible for inducing sleep
Tryptophan is a precursor to serotonin
Sleep
Functions of Sleep
Restorative/recuperation is the replenishment of depleted resources used during the day.
Information processing is important for consolidating memories, and memories are improved by sleep.
Evolutionary theory/The adaptive hypothesis holds the premises that:
Animals that need more time to get food overall sleep less.
That when predators are removed, animals can hide and sleep more.
And that more vulnerable animals sleep little.
Polysomnography
Studies that focus on sleep and sleep disorders.
Takes measures of the following:
Heart rate.
Breathing.
Brain waves (With an EGG.).
Eye movements (With an EOG.)
Muscle activity (With an EMG.)
Circadian Rhythms
Circadian rhythm is the name given to our biological clocks. It serves as a consistent cycle of our bodily activity as well as behaviors that occur during a twenty-four-hour period.
The term “Circadian” means “about a day.”
Circadian rhythms are physical, mental, and behavioral changes that follow a roughly 24-hour cycle and respond primarily to light and darkness in an organism's environment.
Low points in the Circadian rhythms cycle are between 1-4 Pm and 2-4 Pm.
Key ways we can upset our circadian rhythms include:
Shift work
Jet lag
Weekends
Suprachiasmatic Nucleus
The suprachiasmatic Nucleus (SCN) is the area in the hypothalamus that is just above the optic chiasm.
The SCN regulates the pineal gland’s secretion of melatonin.
Pineal Gland
The pineal gland plays an important role in the circadian rhythm as well as our sleep and wake cycles.
The pineal gland releases melatonin which affects sleep.
Levels of melatonin change within a twenty-four-hour cycle.
Melatonin both reduces jet lag and is used as a sleep aid.
Types of Sleep
There are two types of sleep, which include REM and NREM.
It was thought that there were four stages of NREM; however, sleep researcher no longer differentiates between stages three and four, so there is officially 3 stages of NREM.
Sequence of Stages
The REM stage gets progressively longer during the night
Deep NREM gets progressively shorter
More deep NREM in the first half of the night
More REM in the second part of the night
Sleeping only 4 hours instead of the usual 7 results in losing more REM sleep
NREM: Non-Rem
NREM sleep starts with Stage 1
Stages 1 and 2 are considered light sleep or light NREM
Stage 1 is so light that a person might not even realize they were asleep
In Stage 1, a person can be easily awakened by their partner, but they may insist that they haven't been sleeping
Stage 3 is considered deep sleep or deep NREM. Stage 3 is also known as delta sleep or slow wave sleep; It is very difficult to awaken a person in Stage 3.
NREM
Bedwetting: frequently happens during deep sleep.
Night terrors: prevalent among children.
Sleepwalking: takes place during NREM as there is partial paralysis during REM, preventing walking.
Sleep Disorders
Sleepwalking occurs during non-rapid eye movement (NREM) sleep.
The person gets up and walks around during sleepwalking.
The person is not acting out their dreams during sleepwalking.
Sleepwalking can be dangerous as the person may walk out of a second-floor window.
There is a controversial defense in crimes committed by sleepwalkers, also known as "Sleepy Murderers."
A sleep-related eating disorder is a condition where a person eats while sleepwalking.
Night Terrors
Happen during NREM sleep.
A person sits up in bed, looks terrified, and screams.
Usually, no memory of the experience in the morning.
Nightmares
Happen during REM sleep.
A person may see frightening images and wake up.
Upon awakening, a person can describe the nightmare in great detail.
Rem
REM stands for Rapid Eye Movement and is characterized by rapid eye movement.
Approximately 20-25% of the night is spent in REM.
A person goes into REM 4 or 5 times per night.
The REM stage comes approximately every 90 minutes.
The REM stage gets progressively longer throughout the night.
REM is also called Paradoxical sleep because brain waves look like those of an awake person or a person in light sleep, but it is hard to awaken the person.
REM is considered active sleep because bodily functions speed up.
REM: Partial Paralysis
Fibers from the brain, including pons, descend and inhibit motor neurons during REM sleep, causing sleep paralysis.
Jouvet, a researcher, cut fibers in cats during REM sleep.
The cats "acted out" their dreams, indicating that the paralysis during REM is necessary to prevent physical movement during dreams.
Sleepwalking does not occur during REM sleep because of partial paralysis.
REM & Dreams
Dreaming mostly occurs during REM sleep.
Non-REM sleep involves less vivid dreams that are more like thinking.
Everyone dreams, but not everyone remembers their dreams.
The amount of REM sleep decreases with age.
REM sleep is important for neural development and memory consolidation.
A night of sleep with REM deprivation leads to less retention of information.
NREM sleep is also involved in memory.
Dreams can incorporate external and internal stimuli.
No sleep learning occurs, meaning you can't learn a language by playing tapes while asleep.
REM Rebound
REM Rebound:
Increase in REM to make up for a deficit
Happens after REM deprivation
Recovery night allows for sleeping through the night
Drugs that decrease REM can cause REM rebound:
Happens when discontinued
REM rebound can come in the form of nightmares.
Sleep Disorders: Insomnia
Difficulty falling asleep and staying asleep.
Stress and anxiety are major causes of insomnia.
Depression can cause early morning awakening despite being able to fall asleep.
Sleeping pills such as tranquilizers, barbiturates, and alcohol can induce insomnia.
Drug-Induced Insomnia
Tranquilizers, Barbiturates, and Alcohol can interfere with REM and overall sleep quality.
Over time, the body can build up a tolerance to these substances, leading to a decrease in sleep quality.
When someone quits taking these substances, they may experience insomnia.
Once they do fall asleep, they may experience REM rebound in the form of nightmares.
Sleep Deprivation: Microsleeps
Microsleeps occur when a person has been sleep deprived.
Microsleeps are fleeting, uncontrollable, brief episodes of sleep that last for seconds.
Microsleeps are sometimes referred to as "zoning out."
During microsleeps, the brainwaves resemble those of sleep.
Microsleeps can be dangerous, especially when driving or operating heavy machinery.
Sleep Disorders: Apnea
Sleep Apnea is a condition where a person stops breathing for minutes at a time, and this can happen many times during the night.
Sleep Apnea increases the risk of heart attacks and other health problems.
Anoxia, which is a lack of oxygen to the brain, can occur due to Sleep Apnea.
Sleep Apnea is sometimes referred to as Sudden Adult Death Syndrome (SADS) because it can be dangerous to stop breathing many times per night.
People with Sleep Apnea are often loud snorers.
The treatment for Sleep Apnea is a CPAP machine.
Sleep Apnea Remedies
Losing weight
Stop smoking
Reduce sleeping pill use
Dental implants
CPAP machine: Continuous positive airway pressure
Sleep Disorders: Narcolepsy
Narcolepsy Symptoms
Sleep attacks & excessive daytime sleepiness triggered by emotions such as anger or laughter
Cataplexy: temporary loss of muscle tone causing falls while awake
Sleep paralysis: inability to move after waking up
Hypnagogic hallucinations: upsetting hallucinations while falling asleep or waking up
Testing for Narcolepsy
In a sleep lab, individuals with narcolepsy go straight into REM stage instead of going through NREM first.
Disorders: REM Sleep Behavior Disorder
People with this disorder lack the normal muscle paralysis that occurs during REM sleep.
As a result, they act out their dreams while sleeping.
This disorder is more common in older males.
It can be dangerous as there is a risk of physical injury to oneself or to the person sharing the bed.
Sleep Promoting Drugs
Benzodiazepines
Benzodiazepines are GABA agonists that increase GABA.
Diazepam (Valium) is a benzodiazepine.
Benzodiazepines can be addictive and cause an overdose when combined with alcohol and opiates by suppressing breathing.
Z-Drugs
Z-drugs are similar to benzodiazepines and also GABA agonists.
Ambien is a Z-drug that can cause sleep disturbances like sleepwalking or sleep eating.
Sleep Hygiene
Avoid full-spectrum light (phones, TV) before going to sleep
Exercise is good for sleep, but not right before bedtime
Avoid caffeine or other stimulants
Establish a regular sleep schedule to regulate circadian rhythms
Avoid eating before sleeping, especially spicy foods
Get exposure to natural light in the morning to help with circadian rhythms
Reduce stress.
Parts of the Brain
Pons: pathways that cause partial paralysis during REM by inhibiting motor neurons
Raphe Nucleus: main area of serotonergic pathways that promote sleep
Serotonin is responsible for inducing sleep
Tryptophan is a precursor to serotonin