Why does relaxation drift to sleepiness losing alertness in practice?

I find that the deep relaxation induced by the practice often causes me to drift into sleepiness, losing my alertness and focus entirely. I feel judged because I cannot maintain wakefulness. My name is Nisha, DOB 22nd March 1991. Time: 9:40 PM. Location: Delhi. Is this sleepiness a sign of chronic fatigue, or is my mind resisting the required attention? How can I remain alert during the practice to ensure consistency?