Why do we feel numbness in our legs when we sit down for a long time?
N.J. SHIRAPATHI KAUSHIK
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Numbness is anabnormal sensation that can occur anywhere in the body, but is most commonly felt in the hands, feet, arms, or legs. We may experience this as slight pricking (tingling) sensation in the limbs, if we leave our hand or feet in a single position for a long time.
This supine or recumbent numbness is also referred to as the “limb falling asleep”. Sometime some minor objects like the wallet in our back pocket pressing against the nerves in our leg can cause our leg to fall asleep because there is direct pressure placed on the leg nerves and blood supply may be cut off because of squished arteries. This is called positional leg pain.
Numbness in legs is often associated with pricking or burning sensations. Clinically it is called as paresthesias. Temporary numbness or tingling that disappears quickly can occur when we sit with our legs crossed for a long time or sleeping on our arm in a bent position.
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Most people have felt this type of sensation. This sensation occurs due to no obvious stimulus. This type of very common numbness while recumbent or supine, poses no danger.
It is caused by temporarily reduced supply of blood to the limbs. When we return to normal position by changing our posture and when the blood supply gets normal we feel free from this numbness.
Sometimes poor supply of blood to limbs leading to numbness can occur due to cholesterol buildup in some arteries (atherosclerosis). Abnormal levels of calcium or potassium or sodium in the body or a vitamin B12 deficiency can also lead to the numbness.
Apart from these, the Parasthesias may occur more often among those who suffer from diabetes, hypothyroidism, alcoholism and malnutrition.
S. PALANIAPPAN
Editor, Research Journal of Biological Sciences
J.J. College of Arts and Science
Pudukkottai, Tamil Nadu