Circadian Rhythms & Sleep

These flashcards cover essential concepts and terminologies related to circadian rhythms and sleep, helping to reinforce knowledge from the lecture.

What are circadian rhythms?

natural, internal processes that regulate the sleep-wake cycle and other physiological processes, repeating approximately every 24 hours.

What is a Zeitgeber?

any external cue, such as daylight, that can synchronize an organism's endogenous rhythm.

What happens to the internal clock of a hamster when placed in continuous darkness?

The hamster continues to show a daily rhythm, indicating that an internal (endogenous) clock regulates its activity.

What occurs during REM sleep?

dreaming often occurs, the eyes move, toes and fingers may twitch, and atonia (loss of muscle tone) is characteristic.

How do cycles of sleep differ between adults and infants?

Infants have shorter sleep cycles, spend more time in REM sleep than adults, and sleep/wake rhythms become apparent around 16 weeks of age.

What is the role of the suprachiasmatic nucleus (SCN) in circadian rhythms?

central pacemaker that generates circadian rhythms and is influenced by light information.

What are ultradian and infradian rhythms?

biological cycles that occur more frequently than once a day (e.g., 90-minute sleep cycles), while infradian rhythms occur less frequently than once a day (e.g., menstrual cycles).

What physiological changes occur during non-REM sleep?

body temperature declines, heart rate decreases, and growth hormone release increases.

What is narcolepsy?

A sleep disorder characterized by frequent, intense attacks of sleep during waking hours, often accompanied by cataplexy, which is a sudden loss of muscle tone.

What are some effects of sleep deprivation?

can lead to irritability, cognitive deficits, immune system compromise, and in severe cases, conditions like fatal familial insomnia.

What is the sleep-wake cycle?

a daily pattern of sleep and wakefulness, influenced by circadian rhythms, which dictate when we feel alert and when we feel sleepy.

What is sleep architecture?

the structure and pattern of sleep cycles throughout the night, including the various stages of REM and non-REM sleep.

What are sleep stages?

REM sleep and non-REM sleep, with non-REM further divided into stages 1, 2, 3, and 4, each characterized by different brain activity and physiological responses.

How does light affect sleep?

regulating circadian rhythms; exposure to natural light during the day can enhance alertness and mood, while darkness promotes the production of melatonin, which aids in sleep.

What is the impact of shift work on circadian rhythms?

can disrupt natural circadian rhythms, leading to sleep disturbances, increased fatigue, and higher risk for health problems such as cardiovascular diseases.

What is the function of the pineal gland in sleep regulation?

produces melatonin, a hormone that regulates sleep-wake cycles by signaling the body when it's time to sleep.

What is sleep inertia?

The grogginess and disorientation experienced immediately after waking, which can affect cognitive performance and mood.

What are common symptoms of insomnia?

difficulty falling asleep, staying asleep, waking up too early, and feeling unrefreshed upon waking.

What is the relationship between stress and sleep?

can negatively impact sleep, leading to difficulties in falling asleep or staying asleep, as well as exacerbating existing sleep disorders.

What is polysomnography?

a comprehensive sleep study that records brain waves, oxygen levels, heart rate, and breathing during sleep to diagnose sleep disorders.