Administration of Alpha s1 -Casein Hydrolysate Increases Sleep and Modulates GABA A Receptor Subunit Expression.

Sleep is the most basic and essential physiological requirement for mental health, and sleep disorders pose potential risks of metabolic and neurodegenerative diseases. Tryptic hydrolysate of αS1 -casein (αS1 -CH) has been shown to possess stress relieving and sleep promoting effects. However, the differential effects of αS1 -CH on electroencephalographic wave patterns and its effects on the protein levels of γ-aminobutyric acid A (GABAA ) receptor subtypes in hypothalamic neurons are not well understood. We found αS1 -CH (120, 240 mg/kg) increased sleep duration in mice and reduced sleep-wake cycle numbers in rats. While αS1 -CH (300 mg/kg) increased total sleeping time in rats, it significantly decreased wakefulness. In addition, electroencephalographic theta (θ) power densities were increased whereas alpha (α) power densities were decreased by αS1 -CH (300 mg/kg) during sleep-wake cycles. Furthermore, protein expressions of GABAA receptor β1 subtypes were elevated in rat hypothalamus by αS1 -CH. These results suggest αS1 -CH, through GABAA receptor modulation, might be useful for treating sleep disorders.