Formulation of Vitality Herbal Tea with Wakefulness-promoting Potential

Coffee is commonly consumed for its effects in reducing sleepiness, lifting the spirit, improving mood and performance. Cortisol is a commonly used biomarker reflecting human response to stress or challenge. HPA (Hypothalamic-Pituitary-Adrenocortical) axis is a major endocrine system responsible for the regulation of stress response and is activated upon stress, leading to the secretion of cortisol which impacts various parts of the body. The status of cortisol as an important marker for human physiological and psychological conditions can be attributed to the non-invasive and easy determination of cortisol level, which can be measured with high accuracy from human saliva. Cortisol is of particular interest and importance when it comes to investigating stress response. In chapter 3, an observational study on the effects of coffee on cortisol response was conducted. Twelve participants were given coffee treatment in the afternoon. Their baseline cortisol levels before the treatment were measured and five additional measurements after the treatment were taken. Subjective sleepiness was measured based on the Stanford Sleepiness Scale. The results showed that subjective sleepiness diminished and cortisol levels were raised 30 min after coffee treatment, particularly for those who had at least 7 hours of sleep the night before or were not habitual coffee drinkers. In chapter 4, consumer preferences for different herbal tea formulas were surveyed. Two sets of experiment were carried out where the first set used herb combinations with paochung tea and the second set used herb combinations without paochung tea. In each set of experiments, a winning formula with potential for future commercial production was selected. In chapter 5, the winning herbal tea formula from chapter 4 was investigated for its potential in promoting wakefulness. Ruler drop test and serial subtractions were performed to assess reaction time, attention and working memory of participants. Salivary cortisol response to the herbal tea was determined. Subjective sleepiness was also measured using the Stanford Sleepiness Scale. The results showed subject improvements in both ruler drop test and the test of serial 7 subtractions. Cortisol levels declined for the majority. The herbal tea produced a mild yet visible arousal effect while reduced tension. A potential for positive lifting effect from the herbal tea has been demonstrated.