HELP!!! oyasumi - QUESTION

[Nki]

Hi. I´m practicing my english learning Japanese!!
one friend (Japanese) is helping me using myspace.
sometimes we "chat". . (I send a message, then my friend reply. . . then I reply and so on)
my question is maybe about Manners:
when my friend write "oyasumi" at the end of the message... should I reply or should I keep virtualyQuiet???

Thank You for Your Help!!

[Ito]

if someone say oyasumi to me i anser oyasumi nasai matane... hugs Ito