Sleep, Dream, Yawn Explained
by Owen Borville
July 25, 2024
Biology, Biosciences
Sleep is a normal body process that allows the body and brain to rest. Although appearing simple, the process of sleep is one of the most complex and mysterious body processes known to science.
During sleep, the body uses less energy, allowing cells to resupply and stock up for the next day for energy conservation and storage. Less activity while asleep makes it easier for the body to heal injuries, repair, and gain recovery of issues that occurred while you were awake.
Also during sleep, the brain reorganizes and catalogs memories and learned information, making them more accessible and efficient. The amount of sleep needed varies from person to person and changes throughout your lifetime.
Newborn babies, for example, require between 14 and 17 hours of sleep, while adults need different amounts of sleep.
Rapid eye movement (REM) sleep is a unique phase of the sleep cycle, where the following occurs. Eye movement is rapid behind closed eyelids and this is where the name “REM” comes from.
Unlike other sleep stages, your brain remains highly active during REM sleep. Brain waves become more variable, resembling wakefulness. Heart rate speeds up, and breathing becomes irregular.
Most of the body experiences low muscle tone, except for temporary loss of muscle tone in certain areas. This may prevent someone from acting out dreams and injury. REM sleep is closely associated with vivid dreaming.
REM sleep cycle is about 60 to 90 minutes after falling asleep, and this cycle plays a crucial role in memory consolidation, emotional processing, and brain development.
During sleep, the brain cycles through four stages. Stage 1 (N1): This is the lightest stage of sleep, lasting about 1 to 7 minutes, where there could be experiences of drifting in and out of wakefulness during this phase.
Stage 2 (N2): In this stage, which lasts around 10 to 25 minutes, the body relaxes further, and the brain activity decreases, but this is relatively light sleep.
Stage 3 (N3): Also known as slow-wave sleep (SWS) or deep sleep, this stage lasts 20 to 40 minutes and it is essential for physical restoration, tissue repair, and immune system support.
Stage 4 (REM Sleep): Rapid Eye Movement (REM) sleep is when vivid dreams occur. REM is crucial for memory consolidation, emotional processing, and overall cognitive performance1. During REM, the brain is highly active, and muscles are temporarily paralyzed to prevent acting out dreams.
A typical night sleep involves several cycles of these stages, with each cycle lasting about 90 minutes. The composition of each cycle can vary based on factors like age and recent sleep patterns.
The need for sleep is driven by the length of time you are awake. The longer you are awake, the greater your “drive” or need to sleep. The drive to sleep continues to build within your body until you are able to sleep.
The body has a natural clock, called a “circadian clock,” that helps regulate sleep. The word “circadian” refers to rhythmic biological cycles that repeat about every 24 hours. These cycles are also called circadian rhythms.
The circadian clock is strongly influenced by light, which is the reason why people living in different regions have different sleeping schedules. This is also the reason why people who work night shifts can have difficulty falling asleep or staying awake.
Circadian rhythms regulate changes in the brain and body that occur over the course of a day. Your body’s biological clock controls most circadian rhythms. This clock is found in a region of the brain called the hypothalamus (pronounced hy-puh-THAL-uh-muhs). The hypothalamus affects sleep and arousal.
Light detected by special neurons in the eye sends signals to many areas of the brain, including the hypothalamus. Signals from the hypothalamus travel to different regions of the brain, including the pineal (pronounced PIN-ee-uhl) gland.
In response to light, such as sunlight, the pineal gland turns off the production of melatonin, a hormone that causes a feeling of drowsiness. The levels of melatonin in the body normally increase after darkness, which makes you feel drowsy.
The change in melatonin during the sleep/wake cycle reflects circadian rhythms. During sleep, the hypothalamus also controls changes in body temperature and blood pressure.
Because circadian rhythms are controlled by light, people who have some degree of blindness in both eyes may have trouble sleeping. For more information about how vision affects circadian rhythms, visit the National Institute of Neurological Disorders and Stroke page on understanding sleep.
The mystery of sleep continues and research is ongoing. Scientists research how a human or animal falls asleep, and how to remain alive while sleeping. In addition, the wake up process must be explained. The process of sleep exhibits the elements of design from a special creation.
Dreams
Dreams are fascinating mental experiences that occur during sleep and can take various forms, from vivid visual imagery to emotional sensations.
Dreams can involve all the sense, including sight, sound, taste, smell, and touch. Some people dream in color, while others dream in black and white. Interestingly, blind individuals often have dream components related to sound, taste, and smell.
Dreams commonly feel like experiencing them firsthand, but you don’t consciously control dream content. Dream scenarios can be nonsensical, illogical, or incoherent. Dreams often evoke strong feelings or emotions. Elements from your daily experiences may appear in dreams.
Why do dreams happen? Some theories suggest that dreaming helps consolidate memories, enhancing cognitive function. Dreams allow us to engage with, rehearse, and process emotions in different contexts. Dreaming could be the brain’s method of mental housekeeping information.
Dream content could be a distorted review of recent events. While the purpose of dreaming remains a mystery, it’s a normal and healthy part of our sleep cycle.
Dreams are thought to be caused by the brain trying to make sense of activity in the hippocampus and amygdala during REM sleep. These areas of the brain regulate emotions, sensations, and memories, and REM sleep activates the brain stem, which causes activity in them.
Scientists believe that animals can dream also. Michel Jouvet, a sleep studies pioneer, observed feline dreaming in the 1960s. Cats experience REM (rapid eye movement) sleep, during which their muscles remain still despite intense mental activity.
By altering brainstem structures, Jouvet induced a state where cats moved as if awake—hunting, jumping, grooming, and defending themselves against invisible threats. These behaviors closely mapped onto waking experiences.
In addition, scientists have observed dream habits in rats. After rats run a maze during the day, rats can rerun the same course while asleep. The rat hippocampus (responsible for memory) remembers the neuron pattern of navigating the maze, which suggests that rats replay memories during sleep.
Animals share neural structures important for sleeping and dreaming, and their dream experiences may play a role in learning and memory.
There are many mysteries of dreaming yet to be discovered and research is ongoing. The process of dreaming is a testament to a unique and creative Design.
Yawning is a unique reflex that occurs involuntarily in humans and animals. During a yawn, the jaw opens wide, takes a deep breath, and then quickly exhales.
Seeing someone yawn can make another yawn also. This contagious yawning starts in childhood and even extends to pets and animals like fish, birds, and apes. This contagious yawning is believed to help us stay alert and connect with others in a group.
One theory suggests that yawning cools the brain by increasing blood flow to the brain through muscle movements in the skull and jaw. Deep breaths during yawning also allow cooler air inside the body.
Yawning may be a reflex that your brain induces to wake you up or make you more alert. Yawning is associated with hormones that briefly increase your heart rate and alertness.
Contagious yawning might be linked to empathy or understanding of someone else, and also a social signal. Yawning excessively, especially without feeling tired, could require the advise of a healthcare professional.
Mysteries about yawning continue to keep researchers busy. However, yawning is an element of Design in living things from a Special Creation.
cpap.com
webmd.com
medlineplus.gov
healthline.com
psychologytoday.com
medicalnewstoday.com
en.wikipedia.org
verywellhealth.com
sleepadvisor.org
my.clevelandclinic.org
britannica.com
nichd.nih.gov
sleepdoctor.com
nationalgeographic.com
Romeijn, N., Raymann, R. J., Møst, E., Te Lindert, B., Van Der Meijden, W. P., Fronczek, R., Gomez-Herrero, G., & Van Someren, E. J. (2012). Sleep, vigilance, and thermosensitivity. European Journal of Physiology, 463(1), 169–176.
National Institute of Neurological Disorders and Stroke. (n.d.). Brain basics: Understanding sleep. Retrieved June 7, 2017, from https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Understanding-Sleep
by Owen Borville
July 25, 2024
Biology, Biosciences
Sleep is a normal body process that allows the body and brain to rest. Although appearing simple, the process of sleep is one of the most complex and mysterious body processes known to science.
During sleep, the body uses less energy, allowing cells to resupply and stock up for the next day for energy conservation and storage. Less activity while asleep makes it easier for the body to heal injuries, repair, and gain recovery of issues that occurred while you were awake.
Also during sleep, the brain reorganizes and catalogs memories and learned information, making them more accessible and efficient. The amount of sleep needed varies from person to person and changes throughout your lifetime.
Newborn babies, for example, require between 14 and 17 hours of sleep, while adults need different amounts of sleep.
Rapid eye movement (REM) sleep is a unique phase of the sleep cycle, where the following occurs. Eye movement is rapid behind closed eyelids and this is where the name “REM” comes from.
Unlike other sleep stages, your brain remains highly active during REM sleep. Brain waves become more variable, resembling wakefulness. Heart rate speeds up, and breathing becomes irregular.
Most of the body experiences low muscle tone, except for temporary loss of muscle tone in certain areas. This may prevent someone from acting out dreams and injury. REM sleep is closely associated with vivid dreaming.
REM sleep cycle is about 60 to 90 minutes after falling asleep, and this cycle plays a crucial role in memory consolidation, emotional processing, and brain development.
During sleep, the brain cycles through four stages. Stage 1 (N1): This is the lightest stage of sleep, lasting about 1 to 7 minutes, where there could be experiences of drifting in and out of wakefulness during this phase.
Stage 2 (N2): In this stage, which lasts around 10 to 25 minutes, the body relaxes further, and the brain activity decreases, but this is relatively light sleep.
Stage 3 (N3): Also known as slow-wave sleep (SWS) or deep sleep, this stage lasts 20 to 40 minutes and it is essential for physical restoration, tissue repair, and immune system support.
Stage 4 (REM Sleep): Rapid Eye Movement (REM) sleep is when vivid dreams occur. REM is crucial for memory consolidation, emotional processing, and overall cognitive performance1. During REM, the brain is highly active, and muscles are temporarily paralyzed to prevent acting out dreams.
A typical night sleep involves several cycles of these stages, with each cycle lasting about 90 minutes. The composition of each cycle can vary based on factors like age and recent sleep patterns.
The need for sleep is driven by the length of time you are awake. The longer you are awake, the greater your “drive” or need to sleep. The drive to sleep continues to build within your body until you are able to sleep.
The body has a natural clock, called a “circadian clock,” that helps regulate sleep. The word “circadian” refers to rhythmic biological cycles that repeat about every 24 hours. These cycles are also called circadian rhythms.
The circadian clock is strongly influenced by light, which is the reason why people living in different regions have different sleeping schedules. This is also the reason why people who work night shifts can have difficulty falling asleep or staying awake.
Circadian rhythms regulate changes in the brain and body that occur over the course of a day. Your body’s biological clock controls most circadian rhythms. This clock is found in a region of the brain called the hypothalamus (pronounced hy-puh-THAL-uh-muhs). The hypothalamus affects sleep and arousal.
Light detected by special neurons in the eye sends signals to many areas of the brain, including the hypothalamus. Signals from the hypothalamus travel to different regions of the brain, including the pineal (pronounced PIN-ee-uhl) gland.
In response to light, such as sunlight, the pineal gland turns off the production of melatonin, a hormone that causes a feeling of drowsiness. The levels of melatonin in the body normally increase after darkness, which makes you feel drowsy.
The change in melatonin during the sleep/wake cycle reflects circadian rhythms. During sleep, the hypothalamus also controls changes in body temperature and blood pressure.
Because circadian rhythms are controlled by light, people who have some degree of blindness in both eyes may have trouble sleeping. For more information about how vision affects circadian rhythms, visit the National Institute of Neurological Disorders and Stroke page on understanding sleep.
The mystery of sleep continues and research is ongoing. Scientists research how a human or animal falls asleep, and how to remain alive while sleeping. In addition, the wake up process must be explained. The process of sleep exhibits the elements of design from a special creation.
Dreams
Dreams are fascinating mental experiences that occur during sleep and can take various forms, from vivid visual imagery to emotional sensations.
Dreams can involve all the sense, including sight, sound, taste, smell, and touch. Some people dream in color, while others dream in black and white. Interestingly, blind individuals often have dream components related to sound, taste, and smell.
Dreams commonly feel like experiencing them firsthand, but you don’t consciously control dream content. Dream scenarios can be nonsensical, illogical, or incoherent. Dreams often evoke strong feelings or emotions. Elements from your daily experiences may appear in dreams.
Why do dreams happen? Some theories suggest that dreaming helps consolidate memories, enhancing cognitive function. Dreams allow us to engage with, rehearse, and process emotions in different contexts. Dreaming could be the brain’s method of mental housekeeping information.
Dream content could be a distorted review of recent events. While the purpose of dreaming remains a mystery, it’s a normal and healthy part of our sleep cycle.
Dreams are thought to be caused by the brain trying to make sense of activity in the hippocampus and amygdala during REM sleep. These areas of the brain regulate emotions, sensations, and memories, and REM sleep activates the brain stem, which causes activity in them.
Scientists believe that animals can dream also. Michel Jouvet, a sleep studies pioneer, observed feline dreaming in the 1960s. Cats experience REM (rapid eye movement) sleep, during which their muscles remain still despite intense mental activity.
By altering brainstem structures, Jouvet induced a state where cats moved as if awake—hunting, jumping, grooming, and defending themselves against invisible threats. These behaviors closely mapped onto waking experiences.
In addition, scientists have observed dream habits in rats. After rats run a maze during the day, rats can rerun the same course while asleep. The rat hippocampus (responsible for memory) remembers the neuron pattern of navigating the maze, which suggests that rats replay memories during sleep.
Animals share neural structures important for sleeping and dreaming, and their dream experiences may play a role in learning and memory.
There are many mysteries of dreaming yet to be discovered and research is ongoing. The process of dreaming is a testament to a unique and creative Design.
Yawning is a unique reflex that occurs involuntarily in humans and animals. During a yawn, the jaw opens wide, takes a deep breath, and then quickly exhales.
Seeing someone yawn can make another yawn also. This contagious yawning starts in childhood and even extends to pets and animals like fish, birds, and apes. This contagious yawning is believed to help us stay alert and connect with others in a group.
One theory suggests that yawning cools the brain by increasing blood flow to the brain through muscle movements in the skull and jaw. Deep breaths during yawning also allow cooler air inside the body.
Yawning may be a reflex that your brain induces to wake you up or make you more alert. Yawning is associated with hormones that briefly increase your heart rate and alertness.
Contagious yawning might be linked to empathy or understanding of someone else, and also a social signal. Yawning excessively, especially without feeling tired, could require the advise of a healthcare professional.
Mysteries about yawning continue to keep researchers busy. However, yawning is an element of Design in living things from a Special Creation.
cpap.com
webmd.com
medlineplus.gov
healthline.com
psychologytoday.com
medicalnewstoday.com
en.wikipedia.org
verywellhealth.com
sleepadvisor.org
my.clevelandclinic.org
britannica.com
nichd.nih.gov
sleepdoctor.com
nationalgeographic.com
Romeijn, N., Raymann, R. J., Møst, E., Te Lindert, B., Van Der Meijden, W. P., Fronczek, R., Gomez-Herrero, G., & Van Someren, E. J. (2012). Sleep, vigilance, and thermosensitivity. European Journal of Physiology, 463(1), 169–176.
National Institute of Neurological Disorders and Stroke. (n.d.). Brain basics: Understanding sleep. Retrieved June 7, 2017, from https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Understanding-Sleep