Insomnia is the most prevalent psychological disorder and also the most prevalent sleep disorder, affecting one out of ten people. Some have trouble falling asleep, others wake up early. Some lie awake worrying, others merely complain of cold feet. This diversity makes it unlikely that 'insomnia' is a single entity with a single underlying risk factor. We obtained an NWO-VICI grant to start a program to identify different subtypes of insomnia and brain processes involved. The program starts with the implementation of the Netherlands Sleep Registry, which uses web-based survey methods to obtain a database of psychometric and sleep data. Latent classes of subtypes of insomniacs - and of very sound sleepers - will be selected to undergo ambulatory monitoring and subsequently extensive neuroimaging, using high-density EEG, fMRI and TMS. The aim is to elucidate brain processes involved in subtypes of insomnia, and to find endophenotypes necessary for the ultimate goal: genotyping.
Our recent brain imaging studies in insomnia have resulted in the first identification of behavioral and structural and functional brain alterations in insomnia. We demonstrated that insomniacs are prone to show a dysbalance of faster responses in simple reaction time tasks and slower responses in a more difficult reaction time task (Altena et al., 2008). We were the first to apply fMRI in insomnia and demonstrated that, in spite of a normal to high performance on verbal fluency tasks, insomniacs show a decreased activation of the dorsolateral prefrontal cortical area typically involved in performing this task (Altena et al., 2008). We presently investigate how insomnia affects performance and BOLD-responses during other tasks that involve prefrontal, parietal and medial temporal lobe activation (fMRI); how it affects ‘resting-state’ perfusion (ASL); how it affects grey and white matter density (voxel-based morpho¬metry, VBM); and how it affects intra-cortical inhibition and facilitation (Transcranial Magnetic Stimulation, TMS).