The Collaborative International Dictionary of English v.0.48:

Unrest \Un*rest"\, n.
   Want of rest or repose; unquietness; sleeplessness;
   uneasiness; disquietude.
   [1913 Webster]

         Is this, quoth she, the cause of your unrest!
                                                  --Chaucer.
   [1913 Webster]

         Can calm despair and wild unrest
         Be tenants of a single breast?           --Tennyson.
   [1913 Webster]

WordNet (r) 3.0 (2006):

unrest
    n 1: a state of agitation or turbulent change or development;
         "the political ferment produced new leadership"; "social
         unrest" [syn: agitation, ferment, fermentation,
         tempestuousness, unrest]
    2: a feeling of restless agitation

Moby Thesaurus II by Grady Ward, 1.0:

115 Moby Thesaurus words for "unrest":
   activity, actuation, agitation, agony, ailment, anguish, anxiety,
   anxiousness, bluster, bobbery, boil, boiling, brouhaha, bustle,
   churn, commotion, concern, conturbation, didder, discomposure,
   disorder, disquiet, disquietude, distress, disturbance, dithers,
   dynamics, ebullition, embroilment, excitement, ferment,
   fermentation, fever, feverishness, fidgetiness, fidgets, flap,
   flurry, fluster, flutter, flutteration, foment, fume, fuss, going,
   heaving, hubbub, hurly-burly, inquietude, jitters, jumpiness,
   kinematics, kinesipathy, kinesis, kinesitherapy, kinetics,
   maelstrom, malaise, mobilization, moil, motion, motivation, move,
   movement, moving, nerviness, nervosity, nervousness, palpitation,
   panting, perturbation, pitapat, pitter-patter, quaking, quaver,
   quavering, quiver, quivering, restiveness, restlessness, roil,
   rout, row, running, seethe, seething, shakes, shaking, shiver,
   shivers, shudder, stir, stirring, strife, swirl, throb, throbbing,
   to-do, tremble, trembling, tremor, trepidation, trepidity, trouble,
   tumult, tumultuation, turbidity, turbulence, turmoil, twitter,
   unease, uneasiness, upset, velocity, worry