Is there anything more unpleasant than an eyelid that won’t stop twitching? Sometimes it only lasts a for few minutes but other times, the disorder can last for several hours. And what about when it's one of the leg muscles that is quivering for days at a time? This kind of disorder is actually very common and is caused by involuntary muscle contractions, also known as fasciculations.‘Almost everyone has experienced this in their lives, and it happens spontaneously at one point or another in 90% of people,’ Dr. Daniel Drachman, professor of neurology and neuroscience at John Hopkins University told PopSci.com. These fasciculations can occur in any muscle of the human body, even the tongue can be affected, although they are more frequent in the eyelids and limbs. Fortunately, they are in the vast majority of cases completely benign and do not reveal the existence of an underlying disease.Unintentional activations of nerve fibresThe fasciculations actually correspond to the unexpected activation of a nerve fibre, or more precisely of a motor function that causes the muscle fibres to contract. This is then translated as the ‘twitch’ or slight movement which is transmitted to the skin and then repeated.However, although this twitching is benign, they have been studied very little and their origin remains relatively vague. It is thus unknown what actually causes this activation or irritation of the nerve fibre.Similarly, specialists believe that the site where the disorder appears does not necessarily correspond to the site where the excitation of the nerve fibre actually took place, which further complicates the understanding of these disorders.The fasciculations are visible to the naked eye but to study them better, it is possible to carry out an electromyography examination. This is used to measure the electrical activity of a skeletal muscle and can therefore reveal if contractions occur; these are large peaks which appear on the recording.Triggering factorsAlthough the origin of this trembling remains unclear, their study has identified some factors likely to cause them such as a lack of sleep, excessive physical activity, a lack of magnesium or an abuse of certain stimulants like caffeine.The causal link has not yet been found however. In some, these disorders occur very frequently, which is called fasciculations syndrome and which can necessitate the use of drugs to treat it. These drugs can be the same as those used to treat seizures or epilepsy but they are not without their dangers and none are able to control contractions completely.Another approach is to reduce the stress potentially associated with these fasciculations by doing more exercise, sleeping more, working less or avoiding all stimulants (caffeine, etc.). In the case of a magnesium deficiency, a supplement can also make the disorder disappear.