The link between abnormalities in circadian rhythm and IEDs may suggest a common neurochemical alteration in FXS involving the reduction of γ-aminobutyric acid (GABA) pathways [10], and enhanced activity of metabotropic glutamate receptors [11], as shown by the data from Fmr1 knockout (KO) mice [12–14]. Here, FMR1 is linked to fragile X syndrome.