Question

Leo is participating in a sleep study. During his sleep, his brain shows delta wave activity. At that point, the researchers wake him up, and he is very disoriented. When the researchers wake Leo up, he is most likely in sleep. a. stage 2 b. REM c. stage 1 d. slow-wave

Short answer

d. slow-wave

Step-by-step solution

Understand Sleep Stages

Before jumping to the solution, it is beneficial to know fundamental details about different sleep stages: 1. Stage 1: This is the light stage of sleep, also known as drowsy sleep. Here, the brain produces high amplitude theta waves. 2. Stage 2: Light sleep. The body temperature and heart rate start to decrease. Brain starts producing sudden increase in brain wave frequency known as sleep spindles. 3. Slow-wave sleep (SWS): Also known as deep sleep. During this stage, the body repairs muscles and tissues, stimulates growth and development, boosts immune function, and builds up energy for the next day. Slow-wave sleep shows delta wave brain activity. 4. REM (Rapid Eye Movement) Sleep: Known as dream stage sleep when most dreaming occurs. Brainwaves during this stage are similar to brainwaves when we are awake.

Identify the Delta Wave Stage

Knowing that delta waves are associated with Slow-wave sleep, we can identify that Leo was likely in this stage when he displays delta wave activity. Therefore, the correct answer is: d. slow-wave

Key concepts

Delta Waves

Delta waves are a type of brainwave that occur during certain stages of sleep. These waves are characterized by their high amplitude and low frequency, typically ranging from 0.5 to 4 Hz.

These brainwaves are the hallmarks of deep sleep, and their presence typically indicates that the brain and body are in a state of restful repair.

• Delta waves usually dominate during the Slow-wave sleep stage, allowing the body to undertake critical processes such as tissue repair and growth.
• Their slow nature reflects the restorative processes taking place, as the body focuses on recovery and rest.

When delta waves are prominent, waking someone can lead to disorientation, as they are in the deepest sleep cycle.
This stage is crucial for both physical and mental recovery, underpinning the importance of quality sleep for overall health.

Slow-wave Sleep

Slow-wave sleep (SWS) is a crucial stage of the sleep cycle characterized by high amplitude delta waves. It is also known as deep sleep, representing the deepest phase of non-REM sleep.

During slow-wave sleep, the body is extremely relaxed, both physically and mentally.

• This stage supports various restorative functions like muscle growth, tissue repair, and protein synthesis.
• It is essential for memory consolidation and cleansing of the brain from waste.

Disruptions during this stage can leave a person feeling groggy and disoriented, much like Leo in the exercise.
It's during this time that the body also conserves energy and cell regeneration is stimulated.
Slow-wave sleep typically occurs in longer cycles during the first half of the night.

REM Sleep

REM (Rapid Eye Movement) sleep is a unique stage of the sleep cycle characterized by rapid movement of the eyes, intense brain activity, and vivid dreaming.

Although the body is mostly paralyzed to prevent us from acting out our dreams, the brain becomes highly active.

• REM sleep is crucial for emotional regulation and creative processing.
• Brainwaves during REM look similar to those when we are awake, indicating high electrical activity.

This stage typically increases in duration as the night progresses, with the longest REM cycles occurring in the early morning hours.
REM sleep helps process experiences and emotions, playing an important role in learning and memory.

Sleep Study Methodology

Understanding sleep stages requires detailed observation and recording of brain activity using techniques like polysomnography.

This methodology allows researchers to monitor various physiological signals during sleep, including brainwave patterns.

• It records the EEG (electroencephalogram) to measure brain activity.
• Other metrics include eye movements, heart rate, and muscle activity, providing a comprehensive view of sleep stages.

By analyzing these signals, researchers can identify the different stages of sleep, such as when delta waves indicate slow-wave sleep.
Polysomnography is essential for diagnosing sleep disorders and assessing sleep quality, helping medical professionals develop targeted therapies.