How Do Sedative/Hypnotics Work?

Reviewed on 10/7/2021

How do sedative/hypnotics work?

Sedative/hypnotics are medications for induction and maintenance sleep in people with insomnia. Sedative/hypnotics induce sedation by depressing the central nervous system (CNS), in particular, the sensory cortex of the brain, which is responsible for processing the sensory inputs from the body, such as touch, pain and temperature.

Sedative/hypnotics depress the limbic system of the brain, which regulates emotional and behavioral responses, and reticular formation which regulates sleep and consciousness. Sedative/hypnotics produce sedation by enhancing the activity of gamma-aminobutyric acid (GABA), a neurotransmitter that inhibits electrical activity in the brain.

Neurotransmitters are chemicals that nerve cells (neurons) release to transmit nerve signals. Neurotransmitters bind to specific types of receptors, which are protein molecules on neuronal membranes that initiate action within the cell when stimulated by the neurotransmitter.

Sedative/hypnotics are believed to enhance GABA’s effects by binding to GABA-A receptors, and opening the chloride channels in the neuronal membrane. When the chloride ions flow into the neuron, they change the electrical polarity within the neuron and reduce its excitability to nerve impulses.

Some of the sedative/hypnotics are barbiturates, another class of medications that also work by enhancing GABA activity. Barbiturates are mostly used in clinical settings for sedation and are no longer commonly prescribed because of their high potential for addiction, overdose and use as illegal street drugs.

Some of the medications used as sedative/hypnotics work in other ways which include:

  • Melatonin receptor agonists: Melatonin receptor agonists bind to melatonin receptors M1 and M2 and enhance their activity. Melatonin performs many essential functions including regulation of sleep/wake cycle, and enhancing melatonin activity in the night improves nighttime sleep.
  • Orexin antagonists: Orexin antagonists promote sleep by blocking orexin activity. Orexin, also known as hypocretin, is a neurotransmitter that has many functions including regulation of sleep/wake states. Orexin is secreted in the hypothalamus region of the brain in two forms, orexin A and B, which bind to OX1 and OX2 receptors and promote arousal and wakefulness.
  • Antihistamines: Antihistamines promote sleep by binding to H1 histamine receptors in the central nervous system, and blocking the activity of histamine which plays a role in wakefulness. Antihistamines are also combined with non-steroidal anti-inflammatory drugs (NSAIDs) to treat occasional sleeplessness caused by mild-to-moderate pain.

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How are sedative/hypnotics used?

Sedative/hypnotics may be administered through the following routes:

Uses of sedative/hypnotics include:

  • Treatment of insomnia, to induce and maintain sleep
  • Treatment of occasional sleeplessness caused by mild-to-moderate pain
  • Relief from anxiety
  • Pre-procedure sedation
  • Barbiturate coma (medically induced coma)
  • Non-24-hour sleep-wake disorder (a circadian rhythm sleep disorder, more common in completely blind people who cannot perceive light)
  • Smith-Magenis syndrome (a rare genetic disorder that causes many cognitive and behavioral abnormalities, including sleep disturbances)

What are side effects of sedative/hypnotics?

Side effects of sedative/hypnotics may include the following:

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

QUESTION

What is insomnia? See Answer

What are names of some sedative/hypnotic drugs?

Generic and brand names of sedative/hypnotic drugs include:

References
https://reference.medscape.com/drugs/sedative-hypnotics

https://www.addictioncenter.com/sleeping-pills/amytal/

https://www.drugs.com/availability/generic-butisol-sodium.html

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6679948/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3016451/

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