Colin Snow
The brainstem, which is made up of the pons, medulla, and midbrain, controls the transitions between wake and sleep. Sleep-promoting cells within the hypothalamus and the brainstem produce a brain chemical called GABA, which reduces activity in the hypothalamus and the brainstem. The brainstem also plays a special role in REM sleep, sending signals to relax muscles essential for body posture and limb movements, so that we don't act out our dreams.
REM sleep is generated and maintained by the interaction of a variety of neurotransmitter systems in the brainstem, forebrain, and hypothalamus. Within these circuits lies a core region that is active during REM sleep, known as the subcoeruleus nucleus (SubC) or sublaterodorsal nucleus. It is hypothesised that glutamatergic SubC neurons regulate REM sleep and its defining features such as muscle paralysis and cortical activation.
The amygdala is one of the parts of the brain that is most active during REM sleep, but this state is actually generated deep in the brainstem.
Explore related products
What You'll Learn
- The brainstem, which is made up of the pons, medulla, and midbrain, controls the transitions between wake and sleep
- The thalamus sends and receives information from the senses to the cerebral cortex
- The pineal gland, located within the brain's two hemispheres, increases production of the hormone melatonin, which helps put you to sleep
- The basal forebrain, near the front and bottom of the brain, also promotes sleep and wakefulness
- The amygdala, an almond-shaped structure involved in processing emotions, becomes increasingly active during REM sleep
The brainstem, which is made up of the pons, medulla, and midbrain, controls the transitions between wake and sleep
The brainstem, which is made up of the pons, medulla, and midbrain, plays a key role in controlling the transitions between wakefulness and sleep. It is involved in the generation of rapid eye movement (REM) sleep, which is characterised by rapid eye movements, cortical activation, vivid dreaming, skeletal muscle paralysis, and muscle twitches. During REM sleep, the brainstem sends signals to relax muscles essential for body posture and limb movements, preventing people from acting out their dreams.
The brainstem contains a group of neurons called the subcoeruleus nucleus (SubC) or sublaterodorsal nucleus, which is considered the core of the REM-generating circuit. The majority of REM-active SubC cells are glutamatergic, and they regulate REM sleep and its defining features, such as muscle paralysis and cortical activation. The SubC neurons induce REM sleep muscle paralysis by activating neurons in the ventromedial medulla (VMM) and spinal cord, which in turn inhibit skeletal motoneurons.
The brainstem also contains GABAergic neurons in the ventrolateral periaqueductal gray and dorsal paragigantocellular reticular nucleus, which are involved in REM sleep timing. These neurons inhibit the locus coeruleus, dorsal raphe, and part of the ventrolateral periaqueductal gray, allowing the transition into REM sleep.
The brainstem is also involved in the suppression of postural motor tone during REM sleep. The genioglossus muscle activity in REM sleep is suppressed through the withdrawal of excitatory inputs, such as reduced noradrenaline and serotonin excitation at the hypoglossal motor pool. Additionally, a newly identified muscarinic receptor mechanism linked to G protein-coupled potassium channels also contributes to the suppression of genioglossus muscle activity during REM sleep.
Morning REM Sleep: Myth or Reality?
You may want to see also
Explore related products
The thalamus sends and receives information from the senses to the cerebral cortex
The thalamus is a small structure located deep within the brain, which acts as a relay of information between the body and the cerebral cortex. It is responsible for sending and receiving information from the senses to the cerebral cortex, which is the outer layer of the brain that is involved in interpreting and processing short- and long-term memory.
The thalamus is active during REM sleep, sending images, sounds, and other sensations to the cortex, which fill our dreams. During most stages of sleep, the thalamus becomes quiet, allowing us to tune out the external world.
The thalamus is part of the brain's "executive network", which is responsible for maintaining the desynchronized EEG pattern characteristic of wakefulness. The thalamus contains thalamocortical neurons that send projections throughout the cortex and contribute to wakefulness by releasing excitatory amino acids such as aspartate and glutamate.
During REM sleep, the thalamus is active and sends signals to the cortex, which is also active during this stage. The thalamus is thought to continue to pass signals to the cortex during REM sleep, in a fragmented, filtered, or distorted form.
The thalamus is also involved in the regulation of sleep and wakefulness. At the onset of non-REM sleep, the thalamocortical neurons begin firing in bursts instead of single action potentials, causing the cortex to display the synchronized EEG pattern that is typical of sleep.
The thalamus plays a critical role in slow-wave sleep, with slow oscillations being generated by recurrent connections within the cerebral cortex. Sleep spindles, which are characteristic of NREM sleep, are generated by the thalamus and play a role in disconnecting the cortex from sensory input.
The thalamus is also involved in the onset of sleep, with sleep onset arising from the activation of the anterior hypothalamus and inhibition of the posterior regions and the central midbrain tegmentum.
The thalamus is one of the key structures in the brain that is responsible for regulating sleep and wakefulness and plays a critical role in the different stages of sleep.
Restless Leg Syndrome: REM Sleep's Unwelcome Companion
You may want to see also
Explore related products
The pineal gland, located within the brain's two hemispheres, increases production of the hormone melatonin, which helps put you to sleep
The pineal gland is located deep in the centre of the brain, outside of the blood-brain barrier. It is responsible for the production and secretion of the hormone melatonin, which is released into the bloodstream and cerebrospinal fluid.
Melatonin is often referred to as the 'sleep hormone', as it helps to initiate and maintain sleep. The production and release of melatonin from the pineal gland occur with a clear daily (circadian) rhythm, with peak levels occurring at night. Darkness stimulates the pineal gland to secrete melatonin, while exposure to light inhibits this mechanism.
In addition to its role in regulating sleep, melatonin is involved in cell protection, neuroprotection, and the reproductive system.
How Low Oxygen Levels Affect REM Sleep
You may want to see also
Explore related products
The basal forebrain, near the front and bottom of the brain, also promotes sleep and wakefulness
The basal forebrain is one of the many brain structures involved in sleep and wakefulness. It is located near the front and bottom of the brain. It contains neurons that synthesise acetylcholine and/or GABA. The basal forebrain is part of the "executive network" that is sufficient to maintain the desynchronised EEG pattern that is characteristic of wakefulness.
The basal forebrain is active during REM sleep. It is one of the areas of the brain that is most active during this sleep stage. The basal forebrain is also involved in the regulation of REM sleep.
EEG and REM Sleep: Detection and Insights
You may want to see also
Explore related products
The amygdala, an almond-shaped structure involved in processing emotions, becomes increasingly active during REM sleep
The amygdala is one of the parts of the brain that is most active during REM sleep. This state is actually generated deep in the brainstem. However, the set of cortical and limbic structures involved in REM sleep do not just passively submit to orders issued by the brainstem. On the contrary, the particular kind of dream images associated with REM sleep are the result of a dynamic interaction between certain key structures in the brainstem and the rest of the brain.
Enhancing REM Sleep: Simple Strategies for Better Rest
You may want to see also
Frequently asked questions
REM sleep is one of the two basic types of sleep, the other being non-REM sleep. It is characterised by rapid eye movement, muscle atonia, low-voltage fast-activity EEG, and increased brain glucose metabolism.
Sleep is divided into non-REM sleep and REM sleep. Non-REM sleep is further divided into three stages: N1, N2, and N3. Sleep proceeds in 90-minute cycles of REM and NREM, the order normally being N1 → N2 → N3 → N2 → REM.
During REM sleep, the amygdala is one of the most active parts of the brain. The brainstem, specifically the pons, is also active, and is responsible for generating REM sleep.
Non-REM sleep is considered deep sleep, and is characterised by lack of prominent eye movement and muscle paralysis. REM sleep is considered closer to wakefulness, and is characterised by rapid eye movement and muscle atonia.
The functions of sleep are not yet fully understood, but it is thought to be important for memory consolidation and the removal of reactive oxygen species and metabolic waste products.
