Chapter 17: Sleep Flashcards
Is the brain active during sleep, despite being unconscious?
Yes, the brain remains active during sleep, and sleep is categorized into different stages, each characterized by distinct patterns of electrical brain activity.
What are the initial three stages of sleep grouped as, and what roles do they play?
The initial three stages are grouped as non-rapid eye movement (NREM) sleep. These stages play a crucial role in physical growth and repair, mental restoration, and memory consolidation.
What characterizes Stage I of NREM sleep?
- a short transitional phase from wakefulness to sleep.
- easily disturbed by outside stimuli
- individuals may not be aware that they have fallen asleep.
What characterizes Stage II of NREM sleep, and what are sleep spindles and k-complexes?
Stage II is deeper than Stage I but still a light sleep. It is characterized by bursts of brain activity known as sleep spindles and k-complexes. Sleep spindles are suspected to be important for memory consolidation, and both sleep spindles and k-complexes block external stimuli, allowing for a deeper sleep.
What is Stage III of NREM sleep, and why is it considered essential?
Stage III represents the deepest sleep stage in the sleep cycle. It is essential for feeling well-rested and rejuvenated. During this stage, the body releases growth hormone and testosterone, contributing to recovery and restoration of bodily functions.
What are some physiological processes associated with Stage III of NREM sleep?
During Stage III, the body releases growth hormone and testosterone, contributing to the recovery and restoration of bodily functions. Tissues and structures undergo repair, supporting overall restorative functions.
What is REM sleep, and what are its distinct characteristics?
REM sleep is the final stage in the sleep cycle, typically following deep sleep stages. It is characterized by rapid movement of the eyes under closed lids, and it is when most dreaming occurs.
What happens to skeletal muscles during REM sleep?
Skeletal muscles are inhibited from contracting during REM sleep, preventing physical movements that may accompany dreams. This is to avoid acting out dreams physically.
What are some characteristics of REM sleep, such as increased brain activity and physiological changes?
During REM sleep, some regions of the brain become more active compared to other sleep stages. Despite the apparent restfulness, REM sleep is associated with increased blood pressure, respiration, and heart rate.
How do all four sleep stages occur in relation to each other, and how many times does a complete sleep cycle repeat throughout the night?
All four sleep stages occur consecutively, forming a complete sleep cycle. A sleep cycle repeats approximately 4 to 5 times throughout the night.
What is the optimal timing for a well-timed nap, and how can it contribute to feeling more refreshed and alert?
For a well-timed nap, set a timer for 90 minutes to coincide with the end of a sleep cycle. Waking up at the completion of a cycle helps in feeling more refreshed and alert.
What does the body prioritize early in the night, and when does the deepest sleep, including slow-wave sleep, tend to occur?
The body prioritizes deep restorative sleep early in the night in case of waking up. The deepest sleep, including slow-wave sleep, tends to happen at the beginning of the night.
What does the composition of the first cycle of a sleep cycle involve, and how long does an entire sleep cycle last?
The initial cycle involves progressing through the three stages of NREM sleep, followed by a period of REM sleep, which consistently serves as the final stage. The entire sleep cycle lasts approximately 90 minutes.
How do the duration of slow-wave sleep stages vary throughout the night, and what is associated with the latter part of the night in terms of sleep stages?
Slow-wave sleep stages are longer in the first part of the night, contributing to initial deep restorative sleep. The latter part of the night tends to have more REM sleep, which is associated with dreaming.
What is the circadian rhythm, and what role does the suprachiasmatic nucleus (SCN) play in regulating it?
The circadian rhythm is the natural, internal process that regulates the sleep-wake cycle and repeats roughly every 24 hours.
The suprachiasmatic nucleus (SCN) serves as the master clock that influences every cell’s sleep-wake pattern based on DNA.
what influences whether an individual is a “morning lark” or a “night owl,” and what external stimuli can impact the circadian rhythm?
Genetics play a role in determining whether an individual is a “morning lark” or a “night owl.” External stimuli, such as activities, exercise, eating patterns, and exposure to light, can influence the circadian rhythm.
How does exposure to light, especially in the morning, impact the circadian rhythm, and what adverse effects can occur with exposure to light late at night?
Exposure to light, especially in the morning, helps establish a routine wake-up time by prompting the SCN to set the internal clock. Exposure to light late at night can cause the SCN to reset, potentially delaying the sleep phase and disrupting the sleep-wake cycle.
What is the role of the pineal gland in sleep regulation?
The pineal gland, directly connected to the SCN, secretes melatonin at dusk, contributing to the initiation of the sleep phase.
how is melatonin secretion influenced by exposure to light?
regular exposure to morning light helps to establish a routine wake-up time.
What challenges might blind individuals face in regulating their sleep-wake cycles?
Blind individuals may face challenges due to the absence of light stimulation, disrupting the natural synchronization of the circadian rhythm.
what are some examples of circadian rhythm disruptions?
Circadian rhythm disruptions include jet lag, where an individual’s internal biological clock is out of sync with the time in a new environment, and delayed sleep phase, where a person stays up until 4 am and sleeps until noon.
