What Do Scientists Have to Say?
Some scientist assert that the contributing factors are too much caffeine, anxiety, tiredness, stress, and sleep deprivation and they may also elevate the severity or the frequency of the jerks. However, conclusive research on this topic is missing. It is also important to note that intense physical activity or strenuous exercising may also lead to hypnic jerks.
One possible hypothesis is that these jerks are a natural aspect of the body’s journey from alertness to sleep phase and happens when the nerves “misfire” during this process.
Another stand is that the spasms are an ancient primate reflex to the muscle relaxation happening during the onset of sleep and the brain misinterprets the relaxation for a sign that the primate is falling of a tree and thus, engages the muscles for a quick reaction.
Be that as it may, generally speaking, this phenomenon is completely normal and if you are experiencing it, you have nothing to worry about. Nonetheless, if the jerk or the anxiety surrounding it is significantly diminishing your quality of sleep, you should consult your physician or a sleep specialist and explain your concerns.