We take the site down each night for maintenance, backups, etc. It is up until 11:30 PM CDT and is restarted at 4:00 AM CDT. Sorry for the inconvenience. Larger entities have parallel servers that "switch" during these times and appear to be up 24×7.
Unfortunately, our friends in other countries are affected by this. One day we may be able to justify a larger infrastructure to accommodate 24 hour access.