http://ajp.psychiatryonline.org/cgi/con ... 58/12/2008
This study has a lot of good information for you.
"Adverse events were assessed with a checklist of items, each of which were rated on a scale from "not present" to "mildly," "moderately," and "markedly present." A symptom was defined as an adverse event either if it was not present at baseline but was reported in the course of the study or if it was present at baseline but its severity was increased by at least 1 point on the scale during the study. Fisher’s exact tests (p<0.05) showed no statistically significant differences in adverse events between the sertraline group and the placebo group. It is interesting to note that patients who received sertraline reported less dizziness (18% versus 64%, p<0.08), nausea (5% versus 55%, p<0.06) and stomach pain (18% versus 64%, p<0.08) (Fisher’s exact tests) than the patients who received placebo. Only for four side effects did the sertraline patients report numerically more adverse events than the placebo patients: dry mouth (55% versus 27%, p=0.39), drowsiness (73% versus 45%, p=0.39), leg spasms (36% versus 9%, p=0.31), and restlessness (55% versus 27%, p=0.39) (Fisher’s exact tests)."
Restlessness is 55% so I think that's a pretty good probability for you.
Of course, this study only used 22 kids, and out of that 3 dropped out, so it's an incredibly small test group. There just hasn't been a lot of studies done yet to see what these drugs do to kids, and I don't think there's been any studies that cover long-term effects in kids.