Circadian Rhythms and SCN Overview
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Questions and Answers

What type of rhythm operates on a 24-hour cycle?

  • Ultradian rhythms
  • Circannual rhythms
  • Circadian rhythms (correct)
  • Infradian rhythms
  • The suprachiasmatic nucleus (SCN) regulates body temperature but not sleep.

    False

    What hormone does the pineal gland secrete to promote sleepiness?

    melatonin

    The __________ rhythm can be disrupted by crossing time zones.

    <p>circadian</p> Signup and view all the answers

    Match the brain structures with their function:

    <p>Reticular formation = Responsible for arousal Locus coeruleus = Releases norepinephrine during arousal Hypothalamus = Releases histamine and promotes sleepiness Pineal gland = Secretes melatonin</p> Signup and view all the answers

    Which stage of sleep is characterized by sleep spindles and K complexes?

    <p>Stage 2 sleep</p> Signup and view all the answers

    Disruptions to circadian rhythms can lead to enhanced job performance.

    <p>False</p> Signup and view all the answers

    Name the genes that produce proteins affecting the activity of neurons in the SCN.

    <p>Period and timeless</p> Signup and view all the answers

    Damage to the SCN results in less consistent __________ and difficulty synchronizing to light and dark.

    <p>body rhythms</p> Signup and view all the answers

    What substance released by the hypothalamus promotes wakefulness?

    <p>Orexin</p> Signup and view all the answers

    Which sleep disorder is characterized by episodes of sleepiness and hallucinations?

    <p>Narcolepsy</p> Signup and view all the answers

    Sleepwalking can only occur during REM sleep.

    <p>False</p> Signup and view all the answers

    What is insomnia?

    <p>A sleep disorder characterized by inadequate sleep.</p> Signup and view all the answers

    ________ involves engaging in sexual behavior while sleeping.

    <p>Sexsomnia</p> Signup and view all the answers

    Match the following sleep disorders with their descriptions:

    <p>Sleep apnea = Trouble breathing during sleep Night terrors = Intense anxiety during non-REM sleep Periodic limb movement disorder = Involuntary movements of limbs during sleep REM behavior disorder = Movement during REM sleep due to inadequate inhibitory neurons</p> Signup and view all the answers

    Which hypothesis suggests that dreaming results from spontaneous brain activity?

    <p>Activation-synthesis hypothesis</p> Signup and view all the answers

    Lucid dreaming involves not being aware that one is dreaming.

    <p>False</p> Signup and view all the answers

    Describe the function of sleep related to memory.

    <p>Sleep strengthens memory through synapse reorganization.</p> Signup and view all the answers

    Hibernation is characterized by a decrease in body temperature and is a period of relative __________ to infection.

    <p>invulnerability</p> Signup and view all the answers

    What does REM stand for in REM sleep?

    <p>Rapid Eye Movement</p> Signup and view all the answers

    Study Notes

    Circadian Rhythms

    • Early psychologists believed sleep-wake cycles relied on environmental cues.
    • In 1922, a researcher proposed the body generates its own sleep-wake cycles.
    • Circannual rhythms are internal mechanisms for annual sleep-wake cycles.
    • Circadian rhythms are internal mechanisms regulating 24-hour cycles.
    • Sunlight, exercise, meals, and temperature reset circadian rhythms.
    • Disruptions to circadian rhythms cause depression, irritability, and poor performance.
    • Jet lag disrupts circadian rhythm due to crossing time zones.
    • Night shift work disrupts circadian rhythms.

    Suprachiasmatic Nucleus (SCN)

    • The SCN is a brain region controlling circadian rhythms, sleep, and body temperature.
    • SCN damage leads to inconsistent body rhythms and difficulty syncing with light/dark cues.
    • SCN single cells regulate tissues responding to circadian rhythms.

    Genes and Biochemistry

    • Period and timeless genes produce proteins increasing SCN neuron activity.
    • The pineal gland, part of the endocrine system, regulates sleepiness by producing melatonin.
    • Melatonin secretion typically begins 2-3 hours before bedtime.

    Stages of Sleep

    • Stage 1 sleep is the initial stage of sleep, with declining brain activity.
    • Stage 2 sleep is characterized by sleep spindles and K-complexes.
    • Stages 3 and 4 sleep, now combined, feature slow brain waves.
    • REM sleep is rapid eye movement sleep, characterized by muscle relaxation and dreaming.

    Brain Mechanisms for Arousal

    • The reticular formation in the midbrain controls arousal.
    • The pontomesencephalon contributes to arousal.
    • The locus coeruleus in the pons releases norepinephrine, arousing the cortex. It is inactive during sleep.
    • The hypothalamus controls sleepiness, releasing histamine. Antihistamines can induce sleepiness.
    • Orexin, a peptide neurotransmitter, promotes wakefulness, released by hypothalamus and basal forebrain.
    • GABA and acetylcholine also play roles in wakefulness.

    Sleep Disorders

    • Sleepwalking occurs when parts of the brain are awake while others sleep.
    • Lucid dreaming is awareness of being asleep and dreaming.
    • Insomnia is inadequate sleep.
    • Sleep apnea is trouble breathing during sleep.
    • Narcolepsy involves frequent sleepiness, paralysis, and hallucinations.
    • Periodic limb movement disorder involves involuntary leg (and sometimes arm) movements during sleep.
    • REM behavior disorder involves movements during REM sleep, potentially due to inadequate inhibitory neurons.
    • Night terrors cause intense anxiety and screaming during non-REM sleep.
    • Sleepwalking can occur during stages 3 and 4 sleep.
    • Sexsomnia involves sexual activity during sleep.

    Functions of Sleep

    • Sleep provides muscle rest, reduced metabolism, neuronal maintenance, synapse reorganization, memory consolidation, energy conservation, and body temperature regulation.
    • Hibernation involves decreased body temperature, offering relative protection against infection and trauma.

    Dreaming

    • Activation-synthesis hypothesis: Dreaming begins with spontaneous pons activity, activating the cortex.
    • Neurocognitive hypothesis: Dreaming is a result of brain activation from multiple areas, including senses, cortex, and internal stimulation.

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    Description

    Explore the fascinating world of circadian rhythms and the role of the suprachiasmatic nucleus (SCN) in regulating sleep-wake cycles. This quiz covers historical perspectives, types of rhythms, and factors that influence these biological clocks. Test your understanding of how disruptions can affect mental and physical health.

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