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An abundance of scientific evidence points to the many roles that sleep plays in maintaining our mental and physical health. Not getting enough sleep is associated with increased risk for many chronic diseases, including high blood pressure, stroke, and cancer. Although many pharmaceutical sleep aids are available, they carry risks and do not provide good quality sleep. A recent study suggests that supplementation with sake yeast, a natural food product that is used to make Japanese wine, improves non-rapid eye movement sleep in humans by activating adenosine receptors.
Sleep occurs in distinct stages, the most prominent of which is non-rapid eye movement (NREM) sleep – typically referred to as “deep sleep” or “slow-wave sleep.” It comprises approximately 75 to 80 percent of a person’s total sleep time and is characterized by slowed brain waves, heart rate, and respiration. During NREM sleep, the body produces growth hormone, which plays roles in metabolism.
Adenosine is a nucleoside compound present in every cell of the body. It plays important roles in energy metabolism and utilization. When adenosine binds to adenosine receptors in the brain, it promotes NREM sleep.
After first determining that sake yeast activated adenosine receptors in a human cell line, the authors of the study conducted a double‐blind placebo‐controlled crossover trial involving 68 healthy men and women (average age 38 years old). Each participant took 500 milligrams of sake yeast or a placebo in tablet form for four days, one hour prior to their normal bedtime. After a 3-day washout period, the procedure was repeated with the participants who received the placebo taking the yeast and vice versa. Throughout the study, each participant completed a questionnaire to assess the subjective measures of their sleep quality. They also provided electroencephalography (EEG) data via portable EEG device and urine samples (to measure growth hormone excretion) to gauge objective measures of sleep quality.
The participants who took the sake yeast supplements reported improvements in their subjective ratings of sleep and fatigue. The EEG data revealed that the sake yeast supplementation increased key aspects of slow‐wave sleep by 110 percent without altering other sleep parameters. In addition, their urinary excretion of growth hormone increased by 137 percent. These findings suggest that sake yeast supplementation is an effective and safe way to promote high‐quality, deep sleep.