High Ping To Everything At Night

At precisely 11:10 every night my ping starts spastically jumping from 27 to 700 to 300. This problem has lasted for over 2 months. I have tested the ping plugged into the modem with absolutely no other devices connected. I use AT&T's 6mbs DSL plan.

Here is my traceroute to google when I am lagging:

Tracing route to google.com [74.125.21.138]
over a maximum of 30 hops:

  1     4 ms     3 ms     3 ms  192.168.0.1
  2     4 ms     3 ms     3 ms  192.168.1.254
  3   415 ms   431 ms   375 ms  adsl-74-179-96-1.gnv.bellsouth.net [74.179.96.1]
  4   198 ms   165 ms   197 ms  12.81.80.40
  5   208 ms   184 ms   198 ms  12.81.80.46
  6     *      121 ms   159 ms  12.81.80.5
  7    88 ms    77 ms    81 ms  12.81.104.74
  8   229 ms   253 ms   221 ms  12.81.28.15
  9   219 ms   228 ms   330 ms  74.175.192.10
 10   170 ms   168 ms   145 ms  cr1.ormfl.ip.att.net [12.122.106.10]
 11   214 ms   229 ms   227 ms  12.122.28.125
 12   177 ms   168 ms   114 ms  12.122.141.221
 13   309 ms   274 ms   301 ms  12.247.147.26
 14   306 ms   345 ms   297 ms  72.14.239.100
 15   129 ms     *       52 ms  209.85.247.150
 16   255 ms   328 ms   366 ms  209.85.254.107
 17     *        *        *     Request timed out.
 18   243 ms   208 ms    93 ms  yv-in-f138.1e100.net [74.125.21.138]

Trace complete.