Sleep Improving Effects of Milk

Nutrition influences sleep. Drinking a glass of warm milk in the evening has been a long term tradition in several cultures. Although most of these reports are anecdotal, several milk components have been associated with sleep, such as tryptophan, bioactive peptides and magnesium. The widest researched dairy component in relation to sleep is tryptophan. Tryptophan is the precursor of serotonin. A good source of tryptophan is alpha-lactalbumin, a major protein found in whey. Evening alpha-lactalbumin consumption results in increased tryptophan levels in the blood and improves cognitive performance in stress-vulnerable subjects and reduced sleepiness the following morning. The disadvantage of alphalactalbumin is that a rather large dose is required to reach a significant amount of tryptophan. Pure tryptophan may be an alternative. As a source of bioactive peptides, a tryptic casein hydrolysate has been shown to have antistress properties and showed sleep improving effects in rats. Magnesium, another component of milk, may be beneficial in reducing complaints concerning restless legs/periodic limb movement disorder and improvement of sleep efficiency. We conducted a short-term trial in home settings with milk products in women aged 45+ with sleeping problems. We hypothesised that dairy and especially dairy products enriched with magnesium and either tryptophan or a specific casein hydrolysate would be beneficial in reducing sleeping disturbances.