The aim of the trial is to study the efficacity of melatonin in the Lennox-Gastaut syndrome, by assessing the reduction of the seizure/interictal discharges in polysomnography and assessing the sleep structure.
After initial recruitment, the baseline visit includes a polysomnography. The patients will then be randomised in two groups: melatonin (1 cp containing melatonin 2 mg 1x/d 1h before sleep) vs placebo (1 cp 1x/d 1h before sleep). The treatment (melatonin or placebo) will be given for 1 month.
After 1 month, the treatment will be stopped and another polysomnography will be recorded.
The patients will take no treatment (wash-out period) for 15 days. The second treatment phase is cross-over: the group that had melatonin in the first phase will take placebo for one month, and the group that had placebo in the first treatment phase will take melatonin for one month. A last polysomnography will be recorded after the second treatment phase.
The other medications (antiepileptic drugs) taken by the patients before the trial will not be modified.