While drinking milk before bedtime can be a helpful sleeping aid for many people, it is not suitable for everyone.
People who are lactose intolerance would want to avoid milk, no matter the time of day or night.
The NHS said lactose intolerance is a “common digestive problem” where the body is unable to digest lactose – a type of sugar mainly found in milk.
People with lactose intolerance will develop unsettling symptoms within a few hours of consuming milk.
For each period, sleep quality was measured via actigraphy and a sleep questionnaire.
The researchers found that the consumption of milk had a “significant improvement in sleep efficiency”.
The Sleep Foundation noted that milk’s sleep-promoting property “might be due to the amino acid tryptophan”.
Tryptophan plays an important role in the production of melatonin, which is a hormone that helps a person to feel sleepy.