Primary insomnia, a sleeplessness that cannot be attributed to a medical, psychiatric or environmental cause, occurs in 20-25% of those diagnosed with insomnia, a disorder affecting roughly one third of the adult population in industrialised countries. Current hypotheses as to the cause include cerebral hyperarousal, with lower levels of GABA a consistently reported phenomenon on MRS. Here, we have used an asymmetric PRESS sequence (TE1 = 25 ms, TE2 = 85 ms)  to measure metabolites in left prefrontal cortex, anterior cingulate cortex and occipital cortex from subjects with primary insomnia and age-matched controls at 3T (Achieva TX, Philips, Best, The Netherlands) using a 32 channel head coil. Metabolites were quantified using the QUEST algorithm in jMRUI (v4, build 162) to fit individual basis set spectra generated using the NMRSCOPE algorithm and previously published spin data . Earlier observations in other areas of the brain of no significant alteration in NAA, Cho and Cre were replicated  but significantly lower levels of myoinositol were detected in the anterior cingulate cortex of those with insomnia (4.45 ± 1.1, N = 15) compared to controls (5.26 ± 0.6; N = 7; P = 0.021).