Sony has announced that there's a PlayStation Network maintenance scheduled for tonight. The maintenance will take place between the hours of 17:00-20:00 BST (9:00-12:00 PST, 13:00-16:00 EST).
According to Sony, players may experience some disruption during their online sessions and may even be unable to sign in into their accounts. Of course, this will be temporarily.
Despite this, Sony has confirmed that PlayStation Home and Account Management shouldn't be affected by the maintenance, and will remain available during the time period.