MODEL RELEASED. Sleep research. French researcher Jacques Touchon studying the effect of ageing on sleep. Electrodes on the heads of the sleeping men and child are measuring their brain activity. This is recorded as an electroencephalogram (EEG) trace like the ones shown across top. Touchon's research includes the study of sleep disorders in cases of Parkinson's disease and Alzheimer's disease, both of which are neurodegenerative disorders where the brain function degenerates. Disturbed patterns of sleep are a common symptom of Alzheimer's disease. Disturbed sleep is also common in older people in general, who also need less sleep than children.