SANDMAN- A randomised placebo-controlled trial to assess the effect of melatonin on circadian sleep-wake disturbances in ocular disease

When someone has been born without eyes, or had both eyes removed due to trauma or cancer, or who has a severe eye condition which has made them blind or severely visually impaired, they may also be affected by sleep disturbance. This is because the eye contains a layer of cells within the retina called retinal ‘photosensitive’ cells and if they are not there, or damaged, then a response to light may no longer be present. So if there is no response to light the brain doesn’t receive a message to ‘wake up’, thus the levels of a hormone called melatonin do not drop and likewise when evening falls the correct signals cannot occur.

Animal and human studies have demonstrated that by giving melatonin before night time, the sleep-wake cycle can be artificially reset. Melatonin has been used to alleviate sleep disorders such as insomnia and jet lag without causing daytime somnolence, tolerance and dependence, as seen with sleeping tablets such as benzodiazepines. 

In our study we will give a drug called melatonin and compare this to giving a placebo to see if melatonin can improve sleep patterns and mood. We will assess this using questionnaires, sleep diaries, movement measurers (wrist actiwatches), and by measuring 48-hour urine melatonin levels.

Currently, there are no UK guidelines for ocular–related circadian therapeutics. Our research will help to benefit patients and inform future guideline recommendations and set guidelines for protocols in this field as novel drugs are developed in this field.