 The purpose of the study is to gain greater insight into Eye Movement Desensitisation Reprocessing EMDR. EMDR is an NHS recommended treatment, which can significantly reduce trauma symptoms. There is some debate regarding how it actually works, however there is evidence to suggest that the eye movements component helps reduce anxiety and increase relaxation levels. To measure these arousal levels during EMDR previous research has used electrocardiography ECG to measure heart rate, which offers insight into the effectiveness of eye movements EM. All studies to date have used ECG to measure arousal levels which requires technical knowledge to administer and interpret. Furthermore, applying electrodes to a patient experiencing PTSD may heighten anxiety. The present study will use new technology which is a small device that would be gently attached to the end of the patients index finger. This device is very similar to one that measures oxygen levels in the blood and therefore is a very simple piece of equipment and should cause no discomfort to the patient. The study also requires patients faces to be video recorded throughout and it will only be their face that is recorded. This is to match the stages of treatment i.e. when EM starts and stops to their corresponding arousal level outcome. The new technology will digitally measure the patients anxious and relaxed arousal levels during EM and no EM treatment sessions. 10 NHS patients would be recruited to receive two treatment sessions; one with EM and one without and then continue with treatment as usual without any of the recording devices. EM and no EM phases occur at least three times within a treatment session and therefore several measurements can be taken and analysed. 