Thursday, June 16, 2022

What Part Of The Brain Wakes You Up

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What Causes Sleep Problems

How does your brain wake up from sleep?

The brain directs sleep by putting your body to rest. Injury to the brain can lead to changes in sleep.

Physical and chemical changes

The internal clock in the brain controls when people sleep and wake every day. If injured, the brain may not be able to tell the body to fall asleep or wake up. There are chemicals in our body that help us to sleep. An injury can change the way that these chemicals affect the body. If brain mechanisms for starting and stopping sleep are injured, a condition called post-traumatic hypersomnia may result in which a person sleeps many hours more than normal.

Changes in breathing control

Sometimes the brain’s ability to control breathing during sleep becomes altered after a TBI, resulting in periods of apnea . This is called sleep apnea. Other factors may affect the chance of having sleep apnea such as family history or being overweight.

Medications

Medications taken after a brain injury may cause problems going to sleep or staying asleep, or can make people sleepy during the day and unable to participate in activities.

Daytime sleeping and physical inactivity

Napping during the day is likely to disturb sleep at night. Inactivity or lack of exercise can also worsen sleep.

Pain

Many people who have suffered brain injuries also experience pain in other parts of the body. This discomfort may disturb sleep. Medications taken to relieve pain may also affect sleep.

Depression

Alcohol

Caffeine and Nicotine

Causes Of Sleep Paralysis

Sleep paralysis happens when you cannot move your muscles as you are waking up or falling asleep. This is because you are in sleep mode but your brain is active.

It’s not clear why sleep paralysis can happen but it has been linked with:

  • disrupted sleeping patterns for example, because of shift work or jet lag
  • narcolepsy a long-term condition that causes a person to suddenly fall asleep
  • a family history of sleep paralysis

Scientists Now Know How Your Brain Wakes You Up

Senior Writer, The Huffington Post

Recent research has made huge strides in demystifying sleep — why we need it, how to get more of it, and what happens when we don’t get enough of it. But there’s still a lot that remains largely unknown, including the way brain circuits control the sleep-wake cycle. Until now, that is.

In a landmark study, neuroscientists at the University of Bern in Switzerland discovered a pattern of brain activitythat is responsible for waking us up from light sleep and anesthesia.

“These findings identify a new network and refine our understanding of the brain network that regulates sleep and wake cycle,” Dr. Antoine Adamantidis, a neuroscientist at the university and the study’s lead author, told The Huffington Post in an email.

The study, which was , showed that activating the circuit associated with the rhythms of electrical activity that occur during sleep — which is located between the hypothalamus and thalamus brain regions — causes rapid wakefulness. While, inhibiting the circuit deepens sleep.

For the study, the researchers used a new technique called “optogenetics” on mice, inserting light-reactive genes into certain neurons in the rodents’ circuit and then “turning on” those neurons via light pulses.

What’s more, the arousing power of this brain circuit was so strong that it even led the mice to regain consciousness after being put under anesthesia.

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Brain Chemicals And Sleep

Chemicals called neurotransmitters send messages to different nerve cells in the brain. Nerve cells in the brainstem release neurotransmitters. These include norepinephrine, histamine, and serotonin. Neurotransmitters act on parts of the brain to keep it alert and working well while you are awake.

Other nerve cells stop the messages that tell you to stay awake. This causes you to feel sleepy. One chemical involved in that process is called adenosine. Caffeine promotes wakefulness by blocking the receptors to adenosine. Adenosine seems to work by slowly building up in your blood when you are awake. This makes you drowsy. While you sleep, the chemical slowly dissipates.

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Many different sleep promoting factors have been identified. These include chemicals such as adenosine, nitric oxide, prostaglandin D2, and a variety of cytokines .

GABA

GABA is the main inhibitory neurotransmitter involved in switching off state of wakefulness. Although it does not so much act as chemical marker for the end of the day, it is critically involved in coordinating the actual process of falling asleep via its action within preoptic cells which inhibit the activity of wake-promoting brain regions.Adenosine

Adenosine is a byproduct of metabolic and electrical activity within your neurons. This means that the level of adenosine in particular regions of your brain is an indication of the amount of time you have spent awake that day.

Adenosine promotes sleep by influencing various sleep-wake pathways in the brain. One of its main routes of action is by directly inhibiting regions which are tasked with keeping the brain awake, in particular specialized cells in the hypothalamus which contain the chemical orexin/hypocretin, as well as cholinergic cells in the brain stem.

In addition, adenosine is also able to send excitatory messages to the preoptic region, which in turn inhibits wake-promoting regions.

Nitric Oxide

Melatonin

Melatonin is produced by a particular gland located at the base of your brain called your pineal gland. It is mainly released during the night under the regulation of your Suprachiasmatic Nucleus.

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These Neurotransmitters Are Probably Keeping You Up At Night

    Answer by Colin Gerber, Neuroscientist, on Quora:

    There are at least eleven neurotransmitters and hormones that play intimate roles in the sleep-wake cycle. I will go through a list of all of them and talk a little bit about what they do. There has been so much research done on this area and so many mechanisms and interactions have been found that it would be almost impossible to pull everything together in this answer. I will try to give a quick summary and some links to papers in relation to each neurotransmitter and hormone.

    What Controls Our Circadian Rhythm

    How does our body clock know what time of day it is? The circadian biological clock is controlled by a part of the brain called the Suprachiasmatic Nucleus , a group of cells in the hypothalamus that respond to light and dark signals. When our eyes perceive light, our retinas send a signal to our SCN. The SCN sets off a chain reaction of hormone production and suppression that affects body temperature, appetite, sleep drive, and more.

    Each morning, as sunlight creeps in, our body temperature begins to rise and cortisol is released, increasing our alertness and causing us to wake up. In the evening, as it becomes dark outside, melatonin levels rise and body temperature lowers. Melatonin stays elevated throughout the night, promoting sleep. As long as our eyes perceive light, the SCN responds by suppressing melatonin production. This explains why evening exposure to light, such as that from indoor light or electronic devices that emit blue light, such as a computer or television, make it harder to fall asleep.

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    One Neural Circuit Is Responsible For Rapid Arousal From Sleep And Anesthesia

    Researchers believe theyve identified the part of the brain which ends light sleep, called the non-rapid eye movement cycle, and ultimately wakes you up. Professor Antoine Adamantidis from the University of Bern and his team found a neural circuit sandwiched between two brain regions, called hypothalamus and thalamus, and tested its reaction in mice to light pulses. Stimulating the region with this optogenetics technique triggered rapid awakenings from light sleep, while a more concentrated effort caused prolonged wakefulness.

    The discovery is exciting, Adamantidis says, because it could lead to new techniques designed to help people recover consciousness from a vegetative or minimally conscious state. Furthermore, it could be used to help patients with sleep disorders, or at least better understand whats stopping them from getting a good nights rest. Electrical stimulation isnt a new idea, but before it was used without a full understanding of the different brain regions and how they affect our sleeping patterns. With this extra knowledge, more deft treatments could soon be developed.

    Just dont expect them too soon. Even though we made an important step forward now, it will take some time before novel therapeutical strategies will be designed based on our results, Adamantidis stresses.

    What Scientists Know So Far

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    One of the major systems in the brain that wakes you up is called the reticular activating system, or RAS. The RAS is a part of your brain located just above your spinal column. Its about two inches long and the width of a pencil. The RAS acts like a gatekeeper or filter for your brain, making sure it doesnt have to deal with more information than it can handle.

    The RAS can sense important information and create neurochemicals that wake up other parts of the brain. It also keeps you awake throughout the day.

    If you have to go to the bathroom in the middle of the night, the RAS senses that signal from your body and flips a switch to wake your brain up just like a light switch. Signals coming from outside of your body, like the sound of an alarm clock or a parent waking you up, can also flip on your RAS.

    Once the RAS switch turns on, it can take some time for your whole brain and body to wake up. This is because it takes a few minutes to clear all the sleepy neurochemicals from your brain, which is why you may feel groggy when an alarm clock wakes you up.

    But why do you feel more groggy on some days and not on others? When your brain is asleep, it shifts between deep and light stages. If your alarm clock goes off during a deeper stage of sleep, it takes longer for all the parts of your brain to wake up. You can use technology to track what stage of sleep youre in and then wake you during a light stage, so you wake up feeling more refreshed.

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    What Is Rem Sleep

    When you enter REM sleep, brain activity increases again, meaning sleep is not as deep. The activity levels are like when youre awake. Thats why REM sleep is the stage where youll have intense dreams.

    At the same time, major muscles that you normally control cant move. In effect, they become temporarily paralyzed.

    Usually, REM sleep arrives about an hour and a half after you go to sleep. The first REM period lasts about 10 minutes. Each REM stage that follows gets longer and longer.

    The amount of REM sleep you experience changes as you age. The percentage of REM sleep:

    • Is highest during infancy and early childhood.

    The Neurons That Make Us Forget Dreams

    It is not just synapses that may help or hinder the learning process during sleep but also the neurons themselves. Some researchers have identified specific neurons with key roles in memory formation that help us actively forget dreams.

    For instance, research appearing in the journal Science has located some of these neurons in the hippocampus, a brain area crucial for forming memories and learning.

    Akihiro Yamanaka, Ph.D., from Nagoya University, Japan, and his colleagues experimented with some of these neurons that produce a melanin-concentrating hormone that helps regulate both sleep and appetite.

    Yamanaka and team conducted experiments in mice, which showed that the firing of this particular group of neurons during REM sleep controls whether the brain remembers new information after a good nights sleep.

    Genetically deleting these neurons in mice suggested that these cells help the brain actively forget new, possibly unimportant information. What is more, the findings point to the role that these neurons have in forgetting dreams.

    Co-lead author Thomas Kilduff, Ph.D., the director of the Center for Neuroscience at the SRI International research institute in Menlo Park, CA, explains.

    Since dreams are thought to primarily occur during REM sleep, the sleep stage when the MCH cells turn on, activation of these cells may prevent the content of a dream from being stored in the hippocampus consequently, the dream is quickly forgotten.

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    Switching Sleep On And Off

    The researchers headed by Prof. Dr. Antoine Adamantidis discovered that a small population of these thalamic neurons have a dual control over sleep and wakefulness, by generating sleep slow waves but also waking up from sleep, depending on their electrical activity. The research group used a technique called optogenetics, with which they used light pulses to precisely control the activity of thalamic neurons of mice. When they activated thalamic neurons with regular long-lasting stimuli the animals woke up, but if they activated them in a slow rhythmical manner, the mice had a deeper, more restful sleep. This is the first time that an area of the brain has been found to have both sleep and wake promoting functions. “Interestingly, we were also able to show that suppression of thalamic neuronal activity impaired the recovery from sleep loss, suggesting that these neurons are essential for a restful sleep after extended period of being awake”, says Dr. Thomas Gent, lead author of the study. This shows that the thalamus is a key player in both sleep and wake. The study has now been published in the journal Nature Neuroscience.

    Circadian Alignment Is Key

    Scientists discover a

    Your circadian rhythm influences your chronotype, sleep habits, and energy fluctuations, all of which majorly contribute to how you feel when you wake up.

    Think of your circadian rhythm as an internal clock that tells you when to sleep and when to wake up. In other words, it determines your chronotype â whether youâre a morning person, a night owl, or somewhere in between.

    Work, school, and other societal demands are common disruptors of our natural circadian rhythm, resulting in circadian misalignment. Late sleep times and early wake times inevitably raise your sleep debt to unhealthy levels.

    Inconsistent bed and wake times â coupled with modern stressors and prolonged light exposure â throw your dim light melatonin onset off-balance. The DLMO indicates the start of your Melatonin Window, which is when your brain secretes peak levels of the hormone melatonin to promote sleep, making it the best time for you to go to bed. Missing or shifting your DLMO means you have less melatonin to work with, which increases sleep latency and fragmentation, making it harder for you to fall asleep and stay asleep. As a result, you accumulate more sleep debt. Eventually, your physical health and psychological wellness also deteriorate.

    Going against your biological clock and inborn sleeping preferences ultimately makes you feel more tired than if you had adhered to them. After all, your circadian rhythm dictates how much energy you have and when you have energy during the day.

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    What Happens When We Dream

    Asked by: Tasha Henson, Norwich

    The whole brain is active during dreams, from the brain stem to the cortex. Most dreams occur during REM sleep. This is part of the sleep-wake cycle and is controlled by the reticular activating system whose circuits run from the brain stem through the thalamus to the cortex.

    The limbic system in the mid-brain deals with emotions in both waking and dreaming and includes the amygdala, which is mostly associated with fear and is especially active during dreams.

    The cortex is responsible for the content of dreams, including the monsters we flee from, the people we meet, or the experience of flying. Since we are highly visual animals the visual cortex, right at the back of the brain, is especially active, but so are many other parts of the cortex.

    Least active are some parts of the frontal lobes, and this may explain why we can be so uncritical during dreams, accepting the crazy events as though they are real until we wake up.

    to BBC Focus magazine for fascinating new Q& As every month and follow on Twitter for your daily dose of fun science facts.

    Common Sleep Disorders Include:

    • Insomnia: Difficulty with falling asleep or staying asleep or sleep that does not make you feel rested. Insomnia can worsen other problems resulting from brain injury, including behavioral and cognitive difficulties. Insomnia makes it harder to learn new things. Insomnia is typically worse directly after injury and often improves as time passes.
    • Excessive Daytime Sleepiness: Extreme drowsiness.
    • Delayed Sleep Phase Syndrome: Mixed-up sleep patterns.
    • Narcolepsy: Falling asleep suddenly and uncontrollably during the day.

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    What Are Sleep Disorders

    According to the American Sleep Association, at least 40 million Americans experience sleep disorders each year. Another 20 million have occasional sleep issues. These disorders cause sleep deprivation, leading to problems with work, school, driving and social activities.

    There are more than 70 sleep disorders. A few, known as disruptive sleep disorders, lead to moving around or making sounds. Other sleep disorders involve food. And some sleep disorders overlap with psychiatric conditions. If you have problems with sleep or feel very tired, talk to your healthcare provider about a possible sleep disorder.

    Some of the most common sleep disorders include:

    What Happens If Your Sleep Drive Is Off

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    When your sleep drive is off, you may feel tired during the day and wired at night. Insomnia and daytime sleepiness can result from a change in daylight exposure, such as that experienced during Daylight Saving Time and jet lag. When you travel to a new time zone, the time and light cues your circadian rhythm relies on are suddenly different, forcing your brain and body to adjust. As your sleep drive adapts to this circadian disruption, you might feel tired or unwell and have difficulty focusing.

    A thrown-off circadian rhythm can also occur if you work irregular hours or overnight shifts. Shift work disorder can cause insomnia, excessive daytime sleepiness, mood problems, and an increased risk of on-the-job accidents or injury. Shift workers can also have hormonal imbalances associated with cortisol, testosterone, and melatonin levels.

    Its difficult to change your circadian rhythm. However, you can adjust your sleep drive by following regular sleep and wake times, allowing yourself 7 or more hours of sleep each night, and adjusting your meal times and caffeine intake. Night shift workers might also consider bright light therapy. If you make lifestyle changes to promote a healthy sleep schedule and sleep issues persist, consult a doctor.

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