This study will close a current gap in knowledge and improve quality of life for the nearly 40% of Parkinson’s Disease (PD) sufferers currently experiencing insomnia.

Insomnia has attendant impacts on health and quality of life for both patients and their family members, especially carers. There is little evidence that current treatments are effective. A small number of studies have investigated different drugs, cognitive behaviour therapy, and even caffeine. There is emerging evidence that Parkinson's Disease has many features exhibiting daily fluctuations, suggestive of circadian rhythm disturbances, which may result in sleep disorders. Melatonin is a hormone released by the pineal gland which regulates the sleep-wake cycle. Studies in other populations indicate that melatonin can increase sleep efficiency, decrease night-time activity, and shorten sleep latency. There is some evidence it might help with insomnia in PD. The response rate to melatonin in people with PD and insomnia is not known, yet melatonin is widely used. It is important to identify those people who  respond to melatonin in order to optimise clinical outcomes for patients.N-of-1 trials are clinical trials that involves a single patient, with the patient serving as their own control, to test  whether a treatment works in an individual or not. We will conduct N-of-1 trials in 44 patients with PD and insomnia over 12 weeks to test whether this improves their PDSS-2 scores, using Motionwatches to monitor their sleep.