2. General health: The subjective general health evaluation was measured with the question "Please rate how do you assess your health condition?" on a 5-point Likert scale with numbers and a description: 1 = "not good," 2 = "fine," 3 = "good," 4 = "very good," and 5 = "excellent." the participants report chronic sickness, prescription and non-prescription medications, height and weight, visual and sight condition ("Do you wear glasses? Do you suffer from cataracts?"). The participants self reports their level of concentration in the morning ("Please rate your level of concentration in the morning.") on a 9-point Likert scale. All of the numbers have valid point values, but only the odd numbers have descriptions: 1 = "extremely poor concentration", 3 = "not able to concentrate," 5 = "neutral, neither unable to concentrate or concentrate," 7 = "able to concentrate," and 9 = "extremely good concentration."