I often get muscle twitching in random muscles, at random times. It might be in my right triceps one day, in my left quadriceps the next, and then in one of my hands. It normally lasts from a few second up until a few hours at a time. This has always been concerning to me. I regularly evaluate patients with neurological conditions such as, amyotrophic lateral sclerosis (ALS), myopathies, and other types of neuropathies. So naturally my mind goes to the worst case scenarios. Now, while muscle twitching, also known as fasciculations, can occur in these “bad” diseases, it can also happen for some very mundane reasons as well. Let’s take look at the common reasons first.
“Fasciculations occur commonly in otherwise normal muscle in many healthy subjects (although mostly recognized by medical students, anxious about ALS).”1
-Dr. Jun Kimura
Father of Electrodiagnostic Neurology
Common Reasons
Stress:
Stress increases the monoamine neurotransmitter epinephrine, also called adrenaline, which is responsible for the “fight or flight response.”2 One important role of this neurotransmitter is that it increases heart rate, blood pressure, and blood flow to muscles. This seems to affect the excitability at the synaptic level which can cause twitching, especially when someone is not necessarily in a situation that would require them to fight or run.
Fatigue:
Fatigue or a lack of sleep can also be a cause for muscle twitching. The CDC recommends that adults ages 18 to 60 get 7 or more hours of sleep a night. A lack of sleep can trigger the release of stress hormones which affect the neurotransmitters in the brain causing them to over stimulate nerves which in turn cause the muscles to twitch.
Caffeine intake:
Caffeine is a commonly ingested stimulant used throughout the world for many different reasons. It helps people wake up in the morning, improves sport performance, and can increase cognitive function. Caffeine has the ability to open ion channels responsible for the activation of calcium release within the muscles and myocytes.4 This ability can cause muscle twitching as calcium is the ion that binds to troponin that triggers muscle contraction.
Electrolyte
Normal Range
Sodium (Na)
136-145 mmol/L
Potassium (K)
3.5-5 mmol/L
Calcium (Ca)
2.25-2.62 mmol/L
Bicarbonate (HCO3)
21-28 mEq/L
Magnesium (Mg)
0.65-1.05 mmol/L
Chloride (Cl-)
98-106 mmol/L
Phosphorus (P)
0.97-1.45 mmol/L
Data gathered from Medscape: Lab Values, Normal Adult5
Electrolyte imbalances:
Electrolytes are essential for basic life functioning, such as maintaining electrical neutrality in cells, as well as generating and conducting action potentials in the nerves and muscles.6 There are several electrolytes that are needed such as sodium, potassium, calcium, bicarbonate, magnesium, chloride, and phosphorus. Of all the electrolytes, a serum potassium level under 3.6 mmol/L (hypokalemia) can cause weakness, fatigue, and muscle twitching.
Medicine side effects:
Many medications and dietary supplements can have side effects. For example, too much vitamin B6 can cause muscle cramping and twitching. B6 is used as a nutritional supplement by the lay public for a variety of perceived health benefits, including morning sickness, cardiovascular disease, premenstrual syndrome, depression, and carpal tunnel syndrome.7
There are also several other reasons including exercise (overexertion), water intake, or anxiety. The vast majority of the time muscle twitching is of no concern and is seen more of as a nuisance than anything. However, there are less common reasons for muscle twitching, in which case medical guidance and treatment should be sought after. If you have muscle twitching combined with muscle atrophy, you should seek immediate medical attention.
In a subsequent blog I will do Part 2: My Muscles are Twitching: When Should I be Concerned?
Kyle J. Martinos PT, DPT, ECS
• Kimura, J. (2013). Electrodiagnosis in diseases of nerve and muscle: Principles and practice (Fourth). Oxford University Press. Chapter 14; pg. 374
• Cleveland Clinic Medical. (2022, March 14). Neurotransmitters: What they are, functions & types. Cleveland Clinic. https://my.clevelandclinic.org/health/articles/22513-neurotransmitters
• Place Holder
• Domaszewski P, Pakosz P, Konieczny M, Bączkowicz D, Sadowska-Krępa E. Caffeine-Induced Effects on Human Skeletal Muscle Contraction Time and Maximal Displacement Measured by Tensiomyography. Nutrients. 2021 Mar 2;13(3):815. doi: 10.3390/nu13030815. PMID: 33801251; PMCID: PMC8001539.
• Farinde, A. (2025, June 16). Lab values, normal adult. Laboratory Reference Ranges in Healthy Adults. https://emedicine.medscape.com/article/2172316-overview
• Shrimanker I, Bhattarai S. Electrolytes. 2023 Jul 24. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan–. PMID: 31082167.
• Hemminger A, Wills BK. Vitamin B6 Toxicity. [Updated 2023 Feb 7]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK554500/.
