NREM sleep is the type of sleep which is associated with slow rolling eye movements. During the night you cycle repeatedly between NREM and REM sleep at regular intervals. Sleep is divided into two main phases - non-rapid eye movement sleep (NREM) and rapid eye movement (REM) sleep. This is one of the mechanisms through which your brain makes sure that you don’t just spontaneously fall asleep at an inopportune moment, even if you are very tired. In addition, the hormone cortisol which is released from your brain-to-body HPA (hypothalamic-pituitary-adrenal) axis in a time of high-stress - as well as morning waking - can act to ensure you remain in a state of wakefulness (but not always in a good way!).Ĭells containing Orexin/hypocretin, a wake promoting factor, are especially busy when you are standing up, walking around, or generally being out and about.
Neurotransmitters such as norepinephrine (and it’s related hormone epinephrine) help to put your brain in a state of high alert and up-regulate activity in wake-promoting regions to ensure that they stay awake and alert.
#Brain stem function affecting sleep series#
There are generally the excitatory neurotransmitters that form the neurochemical balance.ĭuring the day, you are faced with various physical, social, emotional or mental challenges which cause your brain and body to release a series of chemicals which prepare you for action. On the other hand, there are neurochemicals that can keep us from falling asleep easily. This is one of the reasons why melatonin supplements are commonly used to treat circadian disturbances, such as those caused by jet lag. Melatonin release is also sensitive to light signals from the retina and works to entrain your internal sleep-wake cycle to an external clock. It is mainly released during the night under the regulation of your Suprachiasmatic Nucleus. Melatonin is produced by a particular gland located at the base of your brain called your pineal gland. It promotes sleep through a variety of mechanisms but one of the main ones is by promoting the release of adenosine and therefore initiating the kind of sleep-promoting effects described above. Nitric oxide is actually a small gaseous molecule which is synthesized by enzymes in the brain. In addition, adenosine is also able to send excitatory messages to the preoptic region, which in turn inhibits wake-promoting regions. One of it’s 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 (containing the neurotransmitter acetylcholine) in the brain stem. 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.Īdenosine promotes sleep by influencing various sleep-wake pathways in the brain. 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.Īdenosine is a byproduct of metabolic and electrical activity within your neurons.
GABA is the main inhibitory neurotransmitter involved in switching off state of wakefulness. These include chemicals such as adenosine, nitric oxide, prostaglandin D2, and a variety of cytokines (cells made by your immune system). Many different sleep promoting factors have been identified. They also contribute to the activation of sleep promoting regions to set in motion the night-time regime of sleeping. This build up generates a sleep propensity - a need for sleep - which, when it reaches a threshold level, helps block the activity in other regions of your brain which are making sure that you stay awake. Over the waking day, the level of these chemicals - or sleep promoting factors as they are called - increases. When you are awake, the electrochemical activity which generates your thoughts, feelings and decisions generates a series of chemical byproducts. Sleep happens when your sleep promoting regions are active - when they are “winning”. Sleep and waking result from a dynamic interplay - a tug of war - between regions which are involved in keeping your brain awake, and regions which are involved in keeping your brain in a state of sleep.
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