Why is western babies usually off to by 7pm +ish?

well i am an asian, malaysian to be exact. unless the baby is a newborn, others usually goes to bed around 9pm and onwards. what i dun understand is why are all the western babies usually goes to bed @ 7pm +? how bout the adults? in malaysia, 7pm is considered too early. what's the usual working hours you guyz have in western? we here are from 9am - 6pm. so it is very unusual if our baby gets up at 5am. we will be crazy!!