Bio rhythyms

What is a biorhythm?

An inherent timing mechanism that controls or initiates various biological processes.

What are circadian rhythms?

Biological functions that display a rhythm of about 24 hours.

What is the difference between diurnal and nocturnal rhythms?

Diurnal rhythms are active during the light, while nocturnal rhythms are active during the dark.

What are ultradian rhythms?

Rhythms with a period of less than a day, ranging from minutes to hours.

What are infradian rhythms?

Rhythms with a period of more than a day, such as body weight and reproductive cycles.

What are circannual rhythms?

Rhythms with a period of about a year, like migratory cycles of birds.

What is a biological clock?

A neural system that times behavior and allows animals to anticipate events.

What is a free-running rhythm?

A rhythm of the body's own devising in the absence of external cues, typically lasting 25 to 27 hours.

What is entrainment in biological rhythms?

The process of shifting a rhythm using external cues, known as zeitgebers.

What is the role of the Suprachiasmatic Nucleus (SCN)?

It is the main pacemaker of circadian rhythms located just above the optic chiasm.

What happens if the SCN is damaged?

Eating, drinking, exercise, and sleep occur at haphazard times, losing rhythmic nature.

What is the retinohypothalamic pathway?

The pathway through which light information travels from the eye to the SCN.

What is the significance of melanopsin?

It is a photopigment in retinal ganglion cells that makes them sensitive to light, especially blue light.

How do transplantation studies in hamsters contribute to understanding circadian rhythms?

They show that rhythmic behaviors can be reestablished by transplanting SCN cells from embryos.

What proteins are involved in the circadian clock mechanism?

Clock and Cycle proteins form a dimer that promotes transcription of Period (per) and Cryptochrome (cry) genes.

How does light affect the molecular clock in mammals?

Light detected by retinal ganglion cells triggers glutamate release in the SCN, promoting Per protein production.

What is jet lag?

Fatigue and disorientation from rapid travel through time zones and exposure to a changed light-dark cycle.

What is melatonin therapy for jet lag?

Administering melatonin at specific times to adjust the body's rhythm based on travel direction.

What are some effects of disrupting biological rhythms?

Can lead to immune deficiency and metabolic syndromes caused by hormonal changes.

What is the core body temperature cycle?

A daily fluctuation where core body temperature is at its minimum shortly before waking.

What is the relationship between sleep and external events?

Sleep is synchronized to external events like light and dark, influenced by stimuli such as food and alarms.

What is the typical period length of ultradian rhythms?

From minutes to hours.

What is the significance of the SCN's metabolic activity?

It is higher during the light period of the day-night cycle than during the dark period.

What happens to the circadian rhythms of a free-running animal?

They maintain their cycle without external cues.

How do external cues influence biological rhythms?

They can heavily influence rhythms, even if they are biologically generated.

What is the cycle duration for the Clock/Cycle dimer's transcription process?

Approximately 24 hours.

What is the effect of artificial light on biological rhythms?

Staying up late in artificial light can disrupt natural biological rhythms.

What is the role of the SCN in the circadian timing system?

The SCN pacemaker drives slave oscillators that control rhythmic behaviors and connects with pituitary neurons to influence hormone release.

How does light affect the SCN?

Light entrains the SCN pacemaker, influencing the release of hormones like glucocorticoids.

What is the Basic Rest-Activity Cycle (BRAC)?

An ultradian rhythm characterized by recurring cycles of arousal and rest, lasting about 90 minutes in humans.

What does polysomnography measure?

It measures brain-wave activity (EEG), muscle activity (EMG), and eye movements (EOG) during sleep.

What are the five stages of sleep classified by the American Association of Sleep Medicine?

W (Waking), N1 (NREM stage 1), N2 (NREM stage 2), N3 (NREM stage 3), R (REM).

What characterizes NREM stage 1 sleep?

It features alpha rhythm during relaxation, vertex spikes, and lasts several minutes.

What defines NREM stage 2 sleep?

It is characterized by sleep spindles and K-complexes, with waves of 12-14 Hz.

What occurs during NREM stage 3 sleep?

It is defined by delta waves, large-amplitude slow waves, and is associated with deep sleep.

What is REM sleep often referred to as?

Paradoxical sleep, due to the active EEG resembling an awake state while muscles are flaccid.

What is atonia in REM sleep?

A condition of complete muscle inactivity produced by the inhibition of motor neurons.

How does the duration of REM sleep change throughout the night?

REM periods get longer throughout the sleep cycle, with the first half of sleep being NREM dominant and the second half REM dominant.

What happens to sleep patterns as people age?

Total sleep time declines, number of awakenings increases, and time spent in stage 3 sleep decreases significantly.

What is the typical sleep pattern for infants?

Infants spend more time in REM sleep, which decreases with age; they may have up to 50% REM sleep.

What are night terrors?

Brief, very frightening dreams that occur early in sleep, often in children, and are not remembered in the morning.

What do psychoanalytic theories suggest about dreams?

According to Freud, dreams symbolize the fulfillment of unconscious wishes, while Jung viewed them as expressions of the collective unconscious.

What percentage of dreams are related to recent events?

80% of dreams are related to recent events and ongoing problems.

What is the difference between bottom-up and top-down approaches to dream analysis?

a bottom-up approach sees dreams arising from raw sensory/brainstem activity (stimuli), while a top-down approach views them as products of higher cognitive functions, using your memories, expectations, and goals to structure the dream's narrative, essentially using existing knowledge to interpret sensory input.

What physiological changes occur during NREM sleep?

Decrease in body temperature and increase in growth hormone release; dreaming occurs but is less vivid than in REM sleep.

What is the significance of sleep spindles?

Sleep spindles are bursts of brain activity that occur during NREM stage 2 sleep, indicating processing and memory consolidation.

What is the typical sleep duration for young adults?

Young adults typically sleep 7-8 hours per night, with a significant portion in stage 2 and REM sleep.

How does the sleep cycle duration vary?

A complete sleep cycle lasts about 90-110 minutes, alternating between NREM and REM sleep.

What are the characteristics of REM sleep?

Active EEG with small-amplitude, high-frequency waves, relaxed muscles, and vivid dreams.

What happens to melatonin levels in hamsters during winter?

Melatonin levels decrease, leading to smaller gonads, decreased testosterone, and reduced sexual behavior.

What is the relationship between sleep cycles and wakefulness?

Brief periods of wakefulness often occur after each REM cycle, and waking during these times can lead to feeling more rested.

What is the impact of later school start times on adolescents?

Later start times improve attendance, enrollment, and reduce depression and in-class sleeping among adolescents.

What is the Activation-Synthesis hypothesis?

A theory by J. Allan Hobson suggesting that dreams are the brain's attempt to make sense of random signals from the brainstem.

What characterizes top-down dreams?

Dreams that serve as a coping mechanism, often reflecting personal memories and experiences.

What is the evolutionary hypothesis of dreams proposed by Anttio Revonsuo?

It suggests that dreams are biologically important and biased toward threatening images, aiding in survival.

What is a lucid dream?

A dream in which the dreamer is aware they are dreaming and can sometimes control the dream.

What are the biological functions of sleep?

Sleep serves as a restorative process, aids memory consolidation, and enforces niche adaptation.

How does sleep help in memory consolidation?

Sleep improves declarative memory and may aid in consolidating nondeclarative memory during REM sleep.

What are some effects of sleep deprivation?

Increased irritability, difficulty concentrating, episodes of disorientation, and can lead to death.

What is sleep recovery?

The process of sleeping more than normal after a period of sleep deprivation, with increased stage 3 and REM sleep.

What is the sleep memory storage theory?

The theory that the brain replays memories during sleep to aid in memory storage.

What is the synaptic homeostasis memory theory of sleep?

A theory suggesting that global changes during sleep allow biochemical events associated with memory storage to occur.

What role do place cells play in memory during sleep?

Hippocampal neurons that fire during specific locations also activate during sleep, suggesting memory replay.

What is the significance of NREM sleep for memory storage?

NREM sleep is important for consolidating memories, as evidenced by the activation of place cells during sleep.

What did PET imaging reveal about brain activity during sleep?

It showed that the same brain regions active during a task are also active during REM sleep, indicating memory strengthening.

What happens to the body during sleep?

There is a period of reduced muscular tension, heart rate, blood pressure, temperature, and respiration rate.

What is the relationship between sleep and energy conservation?

Sleep is an energy-conserving strategy, allowing organisms to gather food at optimal times and conserve energy.

What is the impact of total sleep deprivation on health?

It compromises the immune system and can lead to death, as seen in conditions like fatal familial insomnia.

What is the role of glia during sleep?

Glia help flush waste products from the brain faster during sleep than when awake.

What are the two theories describing memory reactivation during sleep?

The sleep memory storage theory and the synaptic homeostasis memory theory.

How does sleep deprivation affect memory?

It increases the likelihood of creating false memories and impairs memory consolidation.

What is the significance of slow oscillations and EEG ripples during sleep?

They may encode memory in compressed form and indicate memory replay and transfer between brain structures.

What is the difference between core and global consciousness systems in lucid dreaming?

Core consciousness is involved in dreaming, while global consciousness can awaken to observe the dream.

What is the relationship between biological rhythms and sleep?

Biological rhythms influence sleep patterns, helping animals adapt to their ecological niches.

What is the role of REM sleep in memory?

REM sleep may help consolidate nondeclarative memory and strengthen memories of tasks.

What is the significance of the hippocampus in memory storage during sleep?

The hippocampus is involved in reactivating and storing memories during sleep, particularly in NREM sleep.

How does sleep affect metabolic requirements?

Sleep replenishes metabolic requirements, such as proteins, and is crucial for bodily restoration.

What is the Top Down Hypothesis in relation to dreams?

It suggests that dreams are biologically important, organized, and biased toward threatening images based on current memories.

What are the three main biological functions of sleep?

Aid in memory consolidation, restorative functions, and evolutionary adaptations to avoid predators.

What disorder is characterized by the inability to sleep and can lead to death?

Fatal familial insomnia.

What is required for recovery after sleep deprivation?

Recovery of REM sleep and late-stage NREM sleep.

What do general anesthetics produce in EEG readings?

Slow waves that resemble slow-wave sleep (SWS).

Which neurotransmitter is suggested to promote SWS?

GABA (gamma-aminobutyric acid).

What system in the brain initiates sleep?

The basal forebrain.

What system activates the forebrain into wakefulness?

The reticular formation.

What triggers REM sleep?

A pontine system in the brain.

What is the role of orexin/hypocretin neurons?

They affect various sleep systems and control transitions between wakefulness, NREM, and REM sleep.

What does the term 'isolated brain' refer to?

A brain with an incision between the medulla and spinal cord, showing signs of sleep and wakefulness.

What is the effect of lesions in the reticular formation?

They produce persistent sleep and abolish REM sleep.

What is narcolepsy characterized by?

Frequent sleep attacks, excessive daytime sleepiness, and immediate entry into REM sleep.

What causes narcolepsy in dogs?

A mutant gene for the hypocretin (orexin) receptor.

What is insomnia?

A disorder of slow-wave sleep resulting in prolonged inability to sleep.

What is drug-dependency insomnia?

A condition resulting from continuous use of sleeping pills, leading to tolerance and deprivation of REM or NREM sleep.

What is sleep apnea?

Inability to breathe during sleep, requiring the person to wake up to breathe.

What is cataplexy?

A form of narcolepsy where a person loses muscle tone due to strong emotional stimulation.

What sleep disorder is characterized by organized behavior from an asleep person?

REM behavior disorder (RBD).

What is sudden infant death syndrome (SIDS) associated with?

Immature respiratory pacemaker systems or arousal mechanisms.

What is the recommended sleep position for infants to prevent SIDS?

Putting babies to sleep on their backs.

What happens during obstructive sleep apnea?

Breathing stops or slows down due to relaxation of chest and throat muscles.

What are common treatments for sleep apnea?

A removable tube in the throat or a CPAP machine.