Cows milked at night 'produce milk that makes you sleepy'

A milky drink has long been recommended for those struggling with sleeplessness - but a new study has discovered how to increase milk's effectiveness as a sleep aid.

According to researchers from the Uimyung Research Institute for Neuroscience in South Korea, milk collected during night time ("night milk") has "exceptionally rich amounts of tryptophan and melatonin." Melatonin is a naturally occurring hormone which helps regulate the sleep and wake cycle, and tryptophan can be converted to serotonin and melatonin.

"Milk has long been known and used to promote sleep," say the research team. "The sleep-promoting effect of milk has been attributed to its psychological associations (i.e., the memory of a mother giving milk at bedtime) and its rich store of sleep-promoting components."