I borrowed the title from the thread on the perimeter rule. Thanks sesasheep.

Many airports have night curfew while many are more alive at night during the day. The constraint of night curfew has got to make operations inefficient. By doing away with night curfew spread the flights can be spread over time, reducing congestion in skies around busy airports and allow airlines to rationalise departure and arrival times, especially for international flights. It makes little sense when an airport along with its gates sits idle, for 7 hours (for as long as 8 hours for departures) while there is a shortage of slots during peak times.

Flights from the U.S. to SEA arrive around midnight and depart very early in morning, both times are inconvenient for international flights while aircraft sit idle for 6 or more hours. Majority of long haul international flights from India depart between midnight and 4-5 a.m. Do the planes make less noise in SIN, BKK and DEL? Or do they have a super secret technology that keeps the noise away from the ground?