Why is sleep critical for the body?
To repair/restore mental and physical function and to enter information into memory
Sleep is essential for both cognitive and physical health.
What are the two main drivers of sleep?
- Sleep-Drive
- Circadian Rhythm
These drivers work together to regulate sleep patterns.
What is Sleep-Drive?
The internal drive to balance the need for sleep with the time spent awake
AKA Sleep Pressure
Sleep pressure increases the longer one stays awake.
What is the Adenosine Sleep Theory?
A theory stating that adenosine accumulates in the brain while awake, signaling the body to sleep
Caffeine blocks adenosine receptors, affecting sleepiness.
What is Circadian Rhythm?
A 24-hour internal clock that regulates wakefulness and sleepiness, regardless of time spent awake
Controlled by the suprachiasmatic nucleus (SCN) in the hypothalamus.
What role does the SCN play in sleep?
It coordinates the circadian rhythm based on light signals and regulates melatonin release
The SCN is considered the master clock of the body.
What happens in the morning regarding alertness?
Alertness rises as light hits the eyes, signaling the SCN to stop melatonin production
This process helps the body feel awake.
What is a zeitgeber?
External cues that synchronize the internal circadian rhythm to a 24-hour cycle
Light is the primary zeitgeber.
What are some examples of zeitgebers?
- Light
- Temperature
- Social Interactions
- Food Intake
- Exercise/Physical activity
These factors help align the internal clock with the environment.
What characterizes brain waves when awake?
Desynchronized, low voltage, and high frequency
Indicates a state of alertness and active brain function.
What characterizes brain waves when asleep?
Synchronized, high voltage, and low frequency
Reflects a resting state of the brain.
What are the two primary phases of sleep?
- Rapid Eye Movement (REM)
- Non-Rapid Eye Movement (NREM)
REM accounts for 20-25% of total sleep, while NREM accounts for 75-80%.
What occurs during NREM stage N1?
- Lasts 1-5 minutes
- Regular breathing
- Awakes easily with minimal stimulation
- Rolling eye movement
This is light sleep.
What occurs during NREM stage N2?
- Lasts 10-25 minutes
- Deeper sleep
- Body temperature and heart rate decrease
- Rolling eye movement
This stage is considered true sleep.
What is NREM stage N3 known for?
- Deepest phase of sleep
- Lasts 20-60 minutes
- Difficult arousal
- Body repairs tissues and builds muscle
This stage is crucial for physical restoration.
What characterizes REM sleep?
- Dreams occur
- Rapid eye movement
- Breathing and heart rate are irregular
- Difficult to awaken
REM sleep is also known as paradoxical sleep.
How many sleep cycles do most people go through each night?
4-6 cycles, each lasting approximately 90 minutes
Each cycle includes all phases of sleep.
What is insomnia?
Disrupted sleep patterns leading to increased time to fall asleep, frequent awakenings, or reduced sleep efficiency
Insomnia can be acute or chronic.
What are the two types of insomnia?
- Acute Insomnia (occurs at least 3 nights/wk for LESS than 3 months)
- Chronic Insomnia (occurs at least 3 nights/wk for MORE than 3 months)
Acute lasts less than 3 months, while chronic lasts longer.
What is Obstructive Sleep Apnea?
A sleep disorder characterized by repeated interruptions of breathing during sleep
This condition can lead to fragmented sleep and other health issues.
What is narcolepsy?
A disorder characterized by excessive daytime sleepiness and sudden sleep attacks. Caused by lack of orexinergic neurons.
Narcolepsy can significantly affect daily functioning.
What is the primary function of sleep?
Repair/restore mental and physical function
Sleep is necessary for memory consolidation and energy restoration.
What are the consequences of sleep deprivation?
- Skin lesions
- Compromised immunity
- Motor weakness
- Loss of executive function
- Disruption in homeostasis
- Death
What are the two main drivers of sleep?
- Sleep-Drive
- Circadian Rhythm
