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By Kajal Jain

M. Pharm

17 January 2023
Medically reviewed by
DOES MUSCLE RELAXERS MAKE YOU SLEEPY
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Whether from a new injury or an aggravated old injury, stiffness and soreness in the neck and back at night may lead to disrupted sleep and more pain in the morning. Muscle relaxants have been shown to help relieve this pain and get you through these tough days. 

Used at night, these medications may improve acute neck and back pain. These medications are highly effective in easing muscle tension, making muscles feel looser, and helping with spasms or contractions.

An estimated 2 million American adults reported muscle relaxants used in the U.S. However, Muscle relaxers are effective as a short-term treatment and not recommended for a much longer period due to the side effects observed, which are described further.

What Are Muscle Relaxers?

Muscle relaxants are medicines that help to reduce muscle spasms, which are involuntary muscle contractions caused due to spine-related issues, such as Fibromyalgia, low back strain, or whiplash. Often, muscle spasms cause severe pain and may limit your mobility.

Your doctor might prescribe a muscle relaxant to ease muscle spasms, reduce pain, and help your muscles move better. When your muscles move better, other spine pain treatments, such as physical therapy, stretching, and exercise, are more effective.

There are two types of muscle relaxers: Antispastics and Antispasmodics

  • Antispastics: It targets skeletal muscles or the spinal cord, treating spasms or muscle tightness from certain conditions. 
  • Antispasmodics: It is used for acute injuries and affects the central nervous system. They inhibit the transmission of neurons in the brain. 

Antispastics and antispasmodics have different indications and side effects. Since these drugs work differently, people should never use them interchangeably or substitute one type for another.
Muscle relaxers are effective short-term treatments and should be used to treat acute pain or injury caused by muscle spasms rather than chronic pain.

Individuals should not take muscle relaxants for more than two or three weeks unless directed by the concerned medical practitioner. Consuming it for longer might increase the chances of falls, drug dependence, and abuse. Because of this risk, these medicines are not recommended for people over 65.

Some drugs are not actually muscle relaxants, but they can still help relieve symptoms of spasticity or muscle spasms. Off-label drugs for spasticity include Benzodiazepines (such as Lorazepam, Klonopin, Alprazolam), and Gabapentin  

Off-label drugs for muscle spasms include NSAIDs (such as Naproxen, Ibuprofen), Acetaminophen, and Cannabis

How Do Muscle Relaxers Work?

Muscle relaxers relieve tense muscles, contractions, and stiffness in the tissues by different methods. Two categories of muscle relaxers work slightly differently in the body:

  • Spasmolytics or antispasmodics
  • Neuromuscular blockers.

The mechanism of skeletal muscle relaxants is categorized under spasmolytics. Other Neuromuscular mechanisms are tissue-related, such as muscle relaxers for menstrual cramps.

Spasmolytics relieve muscular tension by interacting with the GABA receptors as an agonist and acting on the CNS in various neurological disorders ensuing hyperpolarization of neurons, while the neuromuscular blockers interfere with chemical transmissions at the endplates. They don’t affect the CNS. 

Diazepam, Baclofen, Tizanidine, and methocarbamol act on the brain and spinal cord (CNS). Dantrolene works directly on the muscle and thus has lesser side effects than other muscle relaxants.

Because of this reason, this drug is often the first muscle relaxant to be prescribed for people with long-term muscle spasms. Cannabis extract works on the brain, spinal cord, and muscles. 

Muscle relaxers act as CNS depressants and cause a sedative effect. The onset of action is rapid and effects typically last from few hours.
The onset of action is rapid and effects typically last from 4-6 hours. The half-life of immediate-release muscle relaxants is 18 hours on average, with a range of 8-37 hours.
Muscle relaxants act on both muscles as well as the CNS (brain and spine nerves), because of which it causes the sedative effect.
Some muscle relaxants begin to work within 30 minutes of their administration, and the effects can last anywhere from 4 to 6 hours.
When abused, Cyclobenzaprine muscle relaxer may have a relaxing and sedative effect and potentially even cause a euphoric “high.”

What Are The Top Muscle Relaxers?

The first-line treatment for an individual's back/neck pain or muscle spasms would be over-the-counter pain relievers like NSAIDs (such as Naproxen and Ibuprofen) or Acetaminophen. Research shows that a muscle relaxant added to Acetaminophen or an NSAID works better than either alone. Now, let's study about top 5 muscle relaxants- 

1. Carisoprodol

It is a non-benzodiazepine drug, available with the brand name Soma in the U.S. Adults can take it to relieve acute, painful muscle conditions. It is a Schedule IV drug and has the potential to be abused. For this reason, you should not use it if you have a history of drug abuse. 

Doctors can only prescribe it for a maximum of 3 weeks. There is insufficient evidence that it works for longer periods. It may cause dizziness and drowsiness and should not be used in folks over 65.

Medical practitioners also warn people about the dangers of its combination with alcohol. In addition, there is a risk of developing a dependency on Carisoprodol. Its recommended dosage is 250-300 mg three times a day and at bedtime. 

2. Cyclobenzaprine

It is a nonbenzodiazepine. Flexeril, Fexmid, and Amrix are brand names of this drug in the U.S. It can treat muscle spasms that occur with acute muscle conditions when a person combines it with rest and physical therapy.

Cyclobenzaprine is available in two oral forms, i.e., immediate-release tablets and extended-release capsules. This drug is a reasonable first choice because it is a cheap generic, but its sedation side effect limits its daily use. It may also cause dry mouth, especially in older folks.

Other side effects include- confusion, irritability, headache, and dizziness. At the standard dose of 10 to 30 mg daily, Cyclobenzaprine will make you sleepy. If you take it during the day, you can reduce its dose to half and take 5 mg to reduce drowsiness.

3. Diazepam

Diazepam is a benzodiazepine. Diastat and Valium are common brand names of this drug in the United States. Healthcare providers may prescribe oral or parenteral Diazepam for severe muscle spasms and spasticity associated with neurological disorders.

However, these aren’t most recommended because they are highly sedating, don’t work well, and Diazepam can be addictive. Other side effects include drowsiness, weakness or lightheadedness, forgetfulness, feeling confused or unsteady, and feeling (or being) aggressive. Avoid benzodiazepines for back and neck pain because there are much better options.

Based on clinical studies, this drug is taken as 2–10 mg orally three or four times daily. This drug has the fewest reported side effects and the lowest sedation potential of the muscle relaxants at this dose. If an individual requires Diazepam injections, the concerned doctor may prescribe an initial IV dose of 5-10 mg and another dose 3–4 hours later. 

4. Metaxalone

Metaxalone is a non-benzodiazepine. Physicians prescribe Metaxalone in combination with others, physical therapy, and other non-drug treatment strategies for painful muscle conditions. A common brand name of this drug is Skelaxin in the U.S.

Insurance companies don’t like to cover it because it is high priced, and itrs cheaper alternatives are available. The side effects of Metaxalone may include dizziness, drowsiness, headache, irritability, and upset stomach. People cannot take it with drugs that affect the amount of serotonin in the body due to the risk of serotonin syndrome.

Taken as 800 mg tablets 3 to 4 times a day, this drug has the fewest reported side effects and lowest sedation potential of the muscle relaxants based on clinical studies. Simply put, it is the best-tolerated muscle relaxant.

5. Methocarbamol

It is an OTC non-benzodiazepine, antispasmodic medication. A common brand name for it in the U.S. is Robaxin. People usually take this drug orally, but doctors can prescribe IV or intramuscular forms.

In recent studies where it was used for up to 8 days, 44% of people who took this drug had complete pain relief (compared to 18% who took nothing) — and that was without any severe side effects.

However, side effects of Methocarbamol may include forgetfulness, allergic reactions, being anxious, headache, blurred vision, a slow heart rate, being confused or dizziness, heartburn, feeling or being sick, itching, rash, and low blood pressure.

Taken as needed, 1500 mg every 6 to 8 hours is a cheap and well-tolerated option for people suffering from acute neck and back pain. Try this first, as it is less sedating than other options, like cyclobenzaprine and Carisoprodol. 

Do Muscle Relaxers Make You Tired?

Muscle relaxants acts directly on the muscles, these muscle relaxants also target the brain and spine nerves. It is, therefore, only common for you to feel tired when using these drugs.

Muscle tiredness occurs when your muscles don’t have enough strength. Consequently, your muscles might not move or contract easily as they usually do. Some chronic medical conditions may cause your muscles to wear out and cause fatigue. Moreover, in some cases, an infection can cause your muscles to falter.

Good muscle relaxers are usually used for a few days before you being noticing their effects. Your prescription can go up to three weeks, depending on the severity of your pain.

Best Time To Take Muscle relaxers

Many individuals who use muscle relaxants don't generally know when to take these drugs. You must know when to take a muscle relaxer to avoid inconveniencs. Suppose you use a muscle relaxer round the clock, you should take it in the evening when you have few distractions and can relax more.

Some muscle relaxers cause more sleepiness and drowsiness than others. Preparing yourself for that and any other side effects of using the drug don't hurt. You are not recommended to use the drug when driving or handling other machines.

That is why early evenings are the best times to take muscle relaxers. The drowsiness distracts you from the pain and gives you some needed rest.

How Long Do Muscle Relaxers Stay In Your System?

Several factors may be responsible for any medicine's delayed or immediate potency. But, usually, the time it takes for muscle relaxants to kick in may hinge on differentials such as age, weight, body fat, any medical condition, and others. It takes around 30 minutes or more after its administration. 

Peak efficacy may linger around 2 to 4 hours. When these medicines are taken orally, they disintegrate and enter the bloodstream, then are distributed to various tissues, organs, and CNS. The progression might take up to 30 minutes before results are experienced.

In many cases, they may last for about 12 hours or more. In some cases, delayed efficacy may be due to factors that only a medical doctor can understand. At this point, taking more doses of the medication is inadvisable since it may result in an overdose of muscle relaxants.

Intravenous drugs provides the shortest route for its administration as it goes directly into the bloodstream and becomes effective in less than 10 minutes.

The below table provides further details of some muscle relaxants:

DRUG NAME

BLOOD TEST

URINE SAMPLE

SALIVA SAMPLE

Baclofen

72 hours for regular doses

48 hours (Up to 10 days with high doses)

48 to 72 hours

Soma

24 hours

2-3 days, Variable (Chronic / Acute)

up to 4 hours

Flexerill

Up to 10 days

4 to 4 days

3 to 10 days

Muscle Relaxers Doesnt Make You Sleepy Every Time

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Study: 

An assumption was made that the efficacy of skeletal muscle relaxants causes some degree of sedation/drowsiness. To test this hypothesis, they conducted a posthoc analysis of the pooled data from two identically designed, double-blind, randomized, placebo-controlled, parallel-group studies in patients with acute, painful muscle spasms.

Subjects/Patients were randomized to receive Cyclobenzaprine extended-release (CER) 15mg and CER 30mg once daily or placebo. Patients recorded daily assessments of daytime sleepiness.

On Day 4, patients were stratified into two categories based on the reported daytime drowsiness—“little to none” or “some to extreme.” They were assessed for an efficacious positive response, defined as good to excellent improvement on the patient rating of medicine helpfulness on Day 4. 

In the group of CER 15mg, out of 59 people with little to no drowsiness, 32 patients (54%) reported good effects, noted by 33 of 57 of those (58%) who has shown some to extreme drowsiness. In the group of CER 30mg, out of 50 patients little to no drowsiness, 27 reported (54%) good to excellent medication helpfulness, as did 41 of 70 (59%) with some extreme drowsiness. 

Why Are Muscle Relaxants Not Always Good?

Healthcare professionals recommend muscle relaxers for certain people with spasms and muscle pain. These drugs can provide short-term relief but can also cause side effects. Adverse side effects include:

  • Dizziness
  • Weakness
  • Fatigue
  • Dry mouth
  • Itchiness
  • Low blood pressure
  • Headache
  • Anxiety
  • Stomachache (and associated symptoms such as nausea, vomiting, and diarrhea) 

Since these side effects can make you impaired or disoriented, you should not drink alcohol while taking them and avoid driving, especially until you know how they affect your coordination. Often, these medications work quickly, within 30 minutes, and you will feel the effects for four to six hours, depending on your dose and tolerance. 

Precautions Of Muscle Relaxants

Muscle relaxants such as Diazepam and Carisoprodol can be habit-forming. Make sure you take your medicine exactly as prescribed by your healthcare professional.

  • Muscle relaxants can cause withdrawal symptoms, such as hallucinations or seizures. Do not discontinue taking your medication suddenly, especially if you've been taking it for a longer period.
  • Muscle relaxers depress your central nervous system (CNS), making it hard to stay awake or pay attention. While taking a muscle relaxer, avoid activities that require coordination or mental alertness, such as driving or operating heavy machinery. 
  • You should avoid taking muscle relaxants with the following drugs to avoid any adverse reaction: Alcohol, Sleep aids, CNS depressants, such as psychotropics or opioids, and Herbal supplements such as St. John's wort 
  • Speak to your doctor about how safely you can use muscle relaxants if you are older than 65. You have a renal or hepatic disorder, mental health problem, or brain disorder.

Bottom Line From Practical Anxiety Solutions

Muscle relaxers are effective as a short-term solution for relieving spasms and muscle pain but can cause some side effects. Along with acting directly on the muscles, muscle relaxers also target the brain and spine nerves. 

It is common for you to feel tired or drowsy while taking these drugs. The best option depends on the injury or underlying condition and factors such as current medications and the person’s age.

There are risks involved in taking prescription or OTC muscle relaxers. Consult a pharmacist or medical practitioner first and follow the instructions closely.

  • Meleger, Alec L. "Muscle relaxants and antispasticity agents." Physical Medicine and Rehabilitation Clinics 17.2 (2006): 401-413. From https://doi.org/10.1016/j.pmr.2005.12.005 Obtained on 17/01/2023
  • Bramness, Jørgen G., et al. "Carisoprodol use and abuse in Norway. A pharmacoepidemiological study." British journal of clinical pharmacology 64.2 (2007): 210-218. From https://doi.org/10.1111/j.1365-2125.2007.02847.x Obtained on 17/01/2023
  • Basmajian, J. V. "Reflex cervical muscle spasm: treatment by diazepam, phenobarbital or placebo." Archives of Physical Medicine and Rehabilitation 64.3 (1983): 121-124. Obtained on 17/01/2023
  • Maletzky, Barry M., and James Klotter. "Addiction to diazepam." International Journal of the Addictions 11.1 (1976): 95-115. From https://doi.org/10.3109/10826087109045533 Obtained on 17/01/2023
  • Nogueira, E., and V. S. Vassilieff. "Hypnotic, anticonvulsant and muscle relaxant effects of Rubus brasiliensis. Involvement of GABAA-system." Journal of Ethnopharmacology 70.3 (2000): 275-280. From https://doi.org/10.1016/S0378-8741(99)00205-6  Obtained on 17/01/2023
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