If rls symptoms aggravates at rest or in evening, why doesn't it usually feel the same in morning or daytime??? even when someone is at rest during daytime as well, technically it should re-occur with same intensity but why only night ???

In MOST individuals, symptoms are worse in the evening, and intensity can vary day to day. It's likely due to the diurnal variation of hormones- especially dopamine (and dopamine levels are highest in the morning). Unfortunately, those with RLS have a higher than average rate of Parkinson's (more common - not a given). Iron and B-vitamin deficiencies can also affect RLS. Check with your doctor.

Neurotransmitters vary in function due to diurnal fluctuations, and nighttime sleep disruption is by far the most frequent pattern, but does occur with prolonged sitting during daytime in many. Some patients have low ferritin levels, has this been checked?