What is the reason for itching in the legs during Qiyam al-Layl, and how can it be overcome to prolong prayer and maintain khushu' (devotional humility)?

The questioner should present their condition to a doctor. It is permissible to remove leg hair for treatment, especially in cases of necessity. The Malikis hold that a small amount of scratching is permissible out of need, and it has been said that if it is excessive, it invalidates the prayer whether done intentionally or by oversight. If it is moderate, it invalidates the prayer if done intentionally, and one performs the prostration of forgetfulness (sujud al-sahw) if done by oversight.