Sleep and Circadian Rhythms Flashcards

Flashcards about sleep and circadian rhythms

What is the general consensus on whether animals sleep?

If sleep is defined as a period of inactivity, then yes, all animals sleep, because sleep is a necessity for animals.

Which animal groups experience both REM and NREM sleep cycles?

Only birds and mammals experience REM and NREM sleep cycles.

Name the three types of time variation in sleep patterns.

Diurnal, Nocturnal, and Crepuscular

What is a biological rhythm?

A behavior that repeats itself on a regular basis.

What are the three types of biological rhythms?

Ultradian, Infradian, and Circadian

What is the function of the suprachiasmatic nucleus (SCN)?

The SCN houses the internal biological clock located in the hypothalamus.

What is the molecular clock mechanism in the SCN?

A negative feedback loop inside the SCN neurons involving transcription proteins that induce DNA transcription and then inhibit it.

What are Zeitgebers?

External cues, like the light/dark cycle, that adjust internal rhythms to match a 24-hour day.

What are sleep phase disorders?

Conditions caused by dysfunction of the internal clock, leading to delayed or advanced sleep.

What EEG patterns characterize wakefulness?

High frequency, low amplitude waves (beta and alpha waves).

How does NREM sleep (SWS) brain activity appear on an EEG?

Slower brain waves (.5-1 Hz), higher amplitude, synchronized neurons firing all at once then not at all.

What are the characteristics of REM sleep EEG patterns?

Resembles wakefulness; active brain, sawtooth waves, theta wave range (4-8 Hz) jagged.

What are the main characteristics of NREM 1 sleep?

Slowing of heart rate and breathing; decrease in body temp; muscles relax; alpha -> theta waves (4-7 Hz). Easy to awaken, hallucinations may occur

What defines NREM 2 sleep?

Continuous slowing of heart rate and breathing and body temp drop; eye movement stops. EEG shows rapid activity burst (12-15 Hz) and single high voltage spikes (K complexes). Brain is blocking external stimuli. Theta — >Delta waves

What physiological processes occur during NREM 3/4 sleep?

Very slow heart rate, breathing, and bp; muscles fully relaxed; difficult to awaken. Delta waves (0.5-2 Hz). Memory consolidation, growth hormone releasing, immune system strengthening.

What physiological events happen during REM sleep?

Dreaming occurs, rapid eye movement, body completely paralyzed. Activation of visual and somatosensory cortex, hippocampus, and amygdala. Deactivation of pre frontal cortex; paralysis of spinal cord

What are two main wakefulness pathways in the brain?

Orexin system and Brainstem Arousal Systems.

How does the Orexin system promote wakefulness?

When light is present, SCN excites LH to produce Orexin. Orexin excites many different brain regions to stimulate the cerebral cortex.

How do Sleep Promoting Systems work?

VIPOA sends inhibitory projections to midbrain regions, shutting them off and promoting sleep.

What are the key effects of sleep deprivation?

Decreased coordination, diminished immune function, psychological effects (irritability), and cognitive decline.

How does sleep, especially REM sleep, affect emotional regulation?

REM sleep reduces amygdala activation in response to emotional trauma, helping to regulate emotions.

What role does sleep play in memory consolidation?

Memory consolidation occurs during sleep, with non declarative memory most improved in REM and declarative in NREM.