Sleep

Describe what circadian rhythms are, where they are regulated in the brain and some factors that impact them

Describe what circadian rhythms are, where they are regulated in the brain and some factors that impact them

1. Circadian rhythms are internal biological rhythms that occur approximately every 24 hours, regulating various physiological processes. These rhythms are influenced by external environmental cues, primarily light and darkness.

2. Circadian rhythms are regulated by the suprachiasmatic nucleus (SCN), a small cluster of neurons located in the hypothalamus. The SCN acts as the master biological clock, synchronizing our internal rhythms with the external environment.

3. Several factors can impact circadian rhythms:

   1. Light Exposure: Light-sensitive neurons in the retina send signals to the SCN based on light levels, helping to adjust the biological clock to align with the day-night cycle.

   2. Hormonal Regulation: Melatonin, a hormone released by the pineal gland, plays a key role in regulating sleep-wake cycles. Its production is stimulated by darkness and inhibited by light.

   3. Lifestyle Factors: Sleep patterns, work schedules (e.g., rotating shift work), and social activities can disrupt circadian rhythms, leading to misalignment with external cues.

How does our brain’s master biological clock respond to changes in our environment?

Responds to changes in the environment, such as light exposure, by adjusting the timing of biological rhythms. For example, exposure to bright light in the evening can delay the release of melatonin, pushing back the sleep-wake cycle, while exposure to light in the morning helps reset the clock, promoting alertness and wakefulness.

Define sleep

Sleep is a state of reduced consciousness characterized by decreased sensory awareness and diminished voluntary muscle activity. Sleep is divided into two main types: Non-REM (NREM) sleep and REM (Rapid Eye Movement) sleep, each consisting of several stages.

Describe the different stages of sleep. Be sure to discuss the key characteristics of each stage including brain wave activity.

1. NREM Stage 1: Alpha

   1. Characteristics: This is a light sleep stage, where you drift in and out of sleep. You can be easily awakened. Hypnagogic hallucinations and myoclonic jerks.

   2. Brain Wave Activity: Alpha waves transition to theta waves. Brain activity begins to slow down.

2. NREM Stage 2: Theta

   1. Characteristics: Longest stage (45-55%). Heart rate slows, and body temperature drops. You become less aware of your surroundings.Consolidates simple memories and processes simple learning.

   2. Brain Wave Activity: Sleep spindles and K-complexes appear. Theta waves dominate, indicating a deeper level of sleep.

3. NREM Stage 3: Delta

   1. Characteristics: Also known as deep sleep or slow-wave sleep, this stage is crucial for physical recovery and growth. It’s harder to awaken someone in this stage. Sleepwalking, bed wetting.

   2. Brain Wave Activity: Delta waves are predominant, signifying deep, restorative sleep. This stage is important for hormone release and immune function.

4. REM Sleep:

   1. Characteristics: This stage is characterized by rapid eye movements, increased brain activity, and vivid dreaming. The body experiences atonia, a temporary paralysis of most muscles, to prevent acting out dreams.

   2. Brain Wave Activity: Brain waves resemble those of wakefulness, with beta waves being prominent. This stage plays a vital role in complex learning and memory, emotion processing and regulation.

Summarize key trends in how sleep cycles progress throughout the night (what stages happen more in the beginning or end of the night, etc.).

1. Early Night:

   1. More NREM Sleep: The initial part of the night is dominated by NREM sleep, particularly stages 3 (deep sleep). This is when the body undergoes significant restorative processes.

   2. Shorter REM Periods: REM sleep occurs, but its duration is shorter at the beginning of the night.

2. Late Night:

   1. More REM Sleep: As the night progresses, REM sleep periods lengthen, often occurring more frequently in the latter half of the night. 

   2. Reduced Deep Sleep: Deep sleep (NREM Stage 3) decreases in duration, while REM sleep becomes more prominent.

Describe some ways sleep cycles differ between young and older adults. 

1. Sleep Duration:

   1. Younger Adults: Typically require 7-9 hours of sleep and tend to sleep deeply, experiencing more restorative NREM sleep.

   2. Older Adults: Often require less sleep (around 7-8 hours), but may have more fragmented sleep patterns.

2. Stage Distribution:

   1. Younger Adults: Experience longer periods of deep sleep (NREM Stage 3) and REM sleep, with fewer awakenings.

   2. Older Adults: Tend to have reduced deep sleep and REM sleep, often spending more time in lighter sleep stages (NREM Stage 1 and 2) and waking up more frequently throughout the night.

3. Sleep Quality:

   1. Younger Adults: Generally experience more continuous and restorative sleep.

   2. Older Adults: Often report poorer sleep quality, increased sleep disturbances, and difficulty falling or staying asleep, which can impact overall health and well-being.

Explain the concept of sleep debt

(How much sleep you need) - (How much sleep you get) = Sleep debt

The four big reasons psychologists hypothesize that we sleep

1. Restoration

2. Memory Consolidation

3. Cognitive Function

4. Emotional Regulation

The major effects of sleep loss

1. Memory Impairment: Sleep deprivation can hinder the brain's ability to form and retain memories.

2. Mood Disturbances: Insufficient sleep is linked to negative mood states.

3. Metabolism Disruption: Sleep loss can affect metabolism and appetite regulation, potentially leading to weight gain and increased risk of obesity. Hormones that regulate hunger, such as ghrelin and leptin, are disrupted with insufficient sleep.

4. Reduced Reaction Time: Lack of sleep can significantly impair reaction times and coordination, increasing the risk of accidents, especially in activities like driving or operating machinery.

5. Physical Well-Being: Overall physical health can deteriorate due to the compounding effects of sleep loss.

Describe some of the natural sleep aids

1. Light Exposure

2. Consistent Sleep Schedule

3. Mindfulness and Relaxation Techniques

4. Environment

Symptoms / effects of insomnia

1. Symptoms: Difficulty falling asleep, staying asleep, or waking up too early. People with insomnia often experience daytime fatigue, irritability, and difficulty concentrating.

2. Effects: Chronic insomnia can lead to significant impairments in cognitive function, mood disturbances, and increased risk of anxiety and depression. It can also affect overall physical health and increase susceptibility to various health issues.

Symptoms / effects of narcolepsy

1. Symptoms: Excessive daytime sleepiness, sudden sleep attacks, and cataplexy (a sudden loss of muscle tone triggered by strong emotions). People may also experience hallucinations and sleep paralysis.

2. Effects: Narcolepsy can severely disrupt daily life, impacting work, social interactions, and overall quality of life. The unpredictability of sudden sleep attacks can pose safety risks, particularly when driving or operating machinery.

Symptoms / effects of sleep apnea

1. Symptoms: Repeated interruptions in breathing during sleep, often accompanied by loud snoring. Individuals may wake up gasping for air or feeling as if they haven't slept well.

2. Effects: Sleep apnea can lead to significant daytime fatigue, cardiovascular problems, and increased risk of hypertension, diabetes, and stroke. It can also affect mood and cognitive function due to poor sleep quality.

Symptoms / effects of sleepwalking (somnambulism)

1. Symptoms: Engaging in complex behaviors while still asleep, such as walking around, performing tasks, or even leaving the house, often with no memory of the event afterward.

2. Effects: Sleepwalking can pose safety risks, both to the individual and to others. It may also disrupt the sleep cycle, leading to tiredness and confusion upon waking.

Symptoms / effects of sleep talking

1. Symptoms: Talking during sleep, which can range from simple sounds to complex conversations. It often occurs during NREM sleep and is generally harmless.

2. Effects: Sleep talking itself does not typically have serious consequences, but it can disturb sleep for others in the same room. In some cases, it may indicate underlying sleep disorders.

Symptoms / effects of night terrors

1. Symptoms: Sudden episodes of intense fear or panic during sleep, often accompanied by screaming, thrashing, or sweating. Unlike nightmares, individuals typically do not remember the episode upon waking.

2. Effects: Night terrors can lead to sleep disruptions and anxiety about going to sleep, particularly in children. They may also cause distress for parents or others in the vicinity.