What Are Central Nervous System Depressants?

Central nervous system (CNS) depressants are drugs that slow down brain activity, making them effective for treating many conditions.  These drugs operate by affecting the neurotransmitter gamma-aminobutyric acid (GABA), which leads to side effects such as drowsiness, relaxation, and decreased inhibition. Central nervous system depressants are used to treat a number of different disorders, including: insomnia, anxiety, panic attacks, stress, sleep disorders, pain, and seizures. There are three major types of CNS depressants: sedatives, hypnotics, and tranquilizers.

Drugs that are classified as CNS depressants include:

Different classes of CNS depressants work in different ways, but all have the ability to reduce activity in the central nervous system and lower levels of awareness in the brain. While CNS depressants all share this ability, there are significant differences among substances within this drug class. In particular, some are generally considered to be safer and are prescribed more than others. However, it’s important to note that almost all depressants have the potential to be addictive and should only be used as prescribed. Central nervous system depressants are sometimes called sedatives or tranquilizers, although those terms are more properly applied to specific categories of CNS depressants.

Paid Advertising. We receive advertising fees from purchases through BetterHelp links.

Online Addiction Counseling

Get professional help from an online addiction and mental health counselor from BetterHelp.

Get Matched
Begin Therapy
  • Personalized Matching Process
  • Easy Online Scheduling
  • 30,000+ Licensed Therapists



Alcohol is one of the most widely used drugs in the world. The degree to which the brain is affected by this central nervous system depressant depends on how much, and how fast, a person drinks. Due to the initial positive behavioral effects of alcohol, many people don’t realize that the substance is a CNS depressant. For example, when someone first begins to drink, he or she may feel less reserved and more relaxed because of the chemical changes alcohol causes within the brain. However, the more someone drinks, the more the brain is affected and the likelihood that a negative emotional response will take over. Alcohol can actually increase anxiety and stress rather than reduce it, and elicit other negative reactions such as anger, aggression, and depression. Chronic alcohol use can also lead to dependence, addiction, and withdrawal symptoms when attempting to stop usage of the drug.


Barbiturates, or “downers,” are a type of CNS depressant that are prescribed to treat anxiety, tension, and sleep disorders. Common barbiturates include Amytal, Luminal (phenobarbital), Mebaral, Nembutal, and Seconal. Barbiturates were previously regarded as a generally safe depressant, but problems with abuse, addiction, and overdose quickly became apparent after widespread prescription. These drugs can generate a sense of euphoria and relaxation even when taken in small doses, which encourages abuse in some. Barbiturates have also shown to have a dramatic impact on sleep patterns, resulting in suppressed REM sleep. In response to particularly high abuse rates from the 1950s to the 1970s, benzodiazepines, which are generally regarded as less addictive and less likely to cause overdose, were developed and popularized. Because the potential for addiction and overdose is so high, the drugs are no longer commonly used to treat anxiety and sleep problems.


Sometimes called “benzos,” benzodiazepines are central nervous system depressants that are prescribed to treat anxiety, sleep disorders, convulsions, and other acute stress reactions. Common benzos include Valium, Xanax, and Ativan. Benzodiazepines are highly effective in treating anxiety and insomnia due to the sleep-inducing, sedative, and muscle-relaxing properties. While considered safe for short-term treatment, long-term or illicit use can lead to the development of a tolerance, addiction, and withdrawal symptoms upon cessation or rapid reduction in use.

Sleeping Pills

This category of CNS depressants includes non-benzodiazepine sleep aids, or “z-drugs,” such as Ambien, Sonata, and Lunesta. These drugs are designed to specifically treat insomnia and other sleep disorders. These sleeping pills are chemically different from other central nervous system depressants, and they work by stimulating the GABA neurotransmitter in a different way. Unlike benzodiazepines, Z-drugs do not reduce anxiety. The drugs are thought to have fewer side effects and risk of addiction compared to benzodiazepines; however, long-term use can still result in dependence and addiction.


Opioids are the most commonly prescribed pain medications in the United States and in much of the world. Some opioids, such as methadone, are also used for other purposes such as opioid addiction treatment. There are a number of different opioids, including legal prescription medications such as codeine and hydrocodone, and illegal street drugs, such as heroin.

While opioids vary tremendously in strength, addictive potential, and other aspects, they tend to be very chemically similar and typically have similar effects. While opioids are considered extremely effective for treating pain, they are also some of the most addictive and dangerous drugs in the world. Every year, opioid overdose takes the lives of tens of thousands of Americans.

Effects of Central Nervous System Depressants

Central nervous system depressants work by increasing the production of the neurotransmitter GABA, which in turn slows down brain activity and produces feelings of relaxation, drowsiness, and a number of other effects, including:

  • Lowered blood pressure
  • Dilated pupils
  • Confusion or disorientation
  • Slowed pulse and breathing
  • Sleepiness or fatigue
  • Difficulty urinating
  • Dizziness
  • Difficulty concentrating
  • Memory loss
  • Slowed reaction time
  • Relaxation and euphoria
  • Slurred speech
  • Reduced inhibitions
  • Loss of coordination
  • Impaired judgement
  • Blacking out

Long-term use can also produce a variety of negative effects, which depend on the type of depressant used and the severity of misuse. In particular, chronic abusers of depressants may develop a tolerance and require increasing doses to maintain the desired effects. Other potential long-term effects include:

  • Chronic fatigue
  • Weight gain
  • Hypersomnia
  • Sexual dysfunction
  • Breathing and sleep difficulties
  • Depression
  • Suicidal thoughts
  • Physical dependence
  • Addiction

Another possible side effect of central nervous system depressant use is overdose. Excessive consumption of depressants can lead to respiratory depression, seizures, and potentially even death. CNS depressants should not be combined with any medication or substance that causes sedation, including prescription pain medicines, certain over-the-counter allergy medications, and alcohol. If combined, they can slow breathing, or heart rate and respiration, which can be fatal. This risk is also compounded if CNS depressants are used to offset the effects of stimulant drugs, such as cocaine or Adderall. In particular, it is extremely dangerous to combine multiple CNS depressants, because the risk of serious complications such as overdose, respiratory failure, and death are greatly magnified.

Signs of CNS Depressant Abuse

The foremost sign of CNS depressant abuse is taking the drugs without medical direction, or outside a doctor’s prescribed guidelines. Examples of this include taking higher doses to intensify intoxication and taking someone else’s prescription. Other warning signs include:

  • Secretive or abnormal behavior
  • Decreased social activity or work productivity
  • Mood swings
  • Periods of depression or apathy
  • Lack of energy or motivation
  • Withdrawal symptoms when not using depressants
  • Failing in attempts to stop using the drugs

Another telling sign of abuse is mixing CNS depressants with other drugs, including opioids and alcohol, to increase their effects. This may lead to severe adverse health reactions and possibly life-threatening consequences.

Central Nervous System Depressant Withdrawal

Discontinuing use of CNS depressants can lead to withdrawal. Because of the way that depressants affect brain chemistry and slow activity, withdrawal can be severe and sudden when an individual stops taking them. Withdrawal symptoms typically begin 12 to 24 hours after the last dose of the drug and are most severe between 24 and 72 hours after this dose. Withdrawal symptoms generally begin to fade after this initial period, known as acute withdrawal; however, some symptoms, known as post-acute withdrawal symptoms (PAWS) may last for up to 24 months.

Additionally, many people going through benzodiazepine or barbiturate withdrawal will also experience a rebound effect in which the condition that they were originally taking the sedative for will come back stronger than before. For example, someone that was taking Xanax for anxiety will often experience worse anxiety upon cessation of the drug. Someone thinking about ending their use of a CNS depressant, or who has stopped and is suffering from withdrawal, should immediately seek medical treatment.

Common central nervous system depressant withdrawal symptoms include:

  • Insomnia
  • Restlessness
  • Nausea
  • Vomiting
  • Shaking
  • Weakness
  • Excessive sweating
  • Irritability
  • Hallucinations
  • Anxiety
  • Panic attacks
  • Body tremors
  • Seizures
  • Depression
  • Muscular stiffness or pain
  • Changes in perception
  • Heart palpitations
  • Tension
  • Memory issues
  • Increased blood pressure and pulse
  • Hypersensitivity to light and sound
  • Aches and pains

Withdrawal from depressants can have potentially-life threatening complications. These risks are amplified when someone quits use of these drugs on their own or tries to stop taking them “cold turkey.” Medically-assisted detox is the safest way to withdraw from CNS depressants, as physicians can gradually decrease use and prescribe any medications to assist with debilitating withdrawal symptoms.

Treatment and Therapies for CNS Depressant Addiction

Treatment for addiction to a central nervous system depressant begins with detox to allow the drugs to exit the system, preferably in rehab or medical facility. After detoxification, a patient will typically move onto a residential inpatient or outpatient treatment program. Drug abuse often co-occurs with other psychological issues, such as depression, and rehab affords individuals struggling with addiction the opportunity for these issues to be addressed with licensed professionals.

Treatment facilities will tailor treatment plans to the individual and include different types of therapies to help the patient replace negative behaviors with healthier ones. Cognitive behavioral therapy (CBT) is particularly helpful in treating CNS depressant abuse. This type of therapy focuses on modifying a patient’s thinking, expectations, and behaviors while simultaneously increasing their skills for coping with various life stressors. Additionally, CNS depressants are often used in conjunction with another drug or substance, and treatment plans will also address any polydrug abuse to ensure lasting recovery.

Get Help Today

If you or a loved one is struggling with an addiction to a central nervous system depressant, know that you are not alone and there are treatment options available. Contact a treatment provider today.