Mybooklive 2T start when computers are off

Is it normal that mybooklive 2T starts by itself? Lights go from blue to flashing green and disks spins up. All computers in my network is turned of… is it defragmenting or something or is it being acessed/hacke by some one??!

http://community.wdc.com/t5/My-Book-Live/MBL-Sleep-Mode-and-firmware-02-32-05-046/td-p/523307