Because its either too early in the morning or too late at night. Or its in the middle of the dia were everyone's at work or school. Besides that... I dont know. If you want a funny response than " hi and bye, ohh hi again bye again. Ohh hi bye, ohh, i wonder 2 things why do we keep saying hi and bye to eachother and why are you still leitura this." there.
some people (unlike me) actually get a reasonable amount of sleep at night instead of sleeping in class and at lunch the seguinte day... (it wont really start to die down until later though in a couple hours. around 2am- 4am my time theres like no one online).