A tryptophan-rich breakfast and exposure to light with low color temperature at night improve sleep and salivary melatonin level in Japanese students

Abstract

BackgroundEpidemiological studies in Japan have documented an association between morning type and a tryptophan-rich breakfast followed by exposure to sunlight in children. The association may be mediated by enhanced melatonin synthesis, which facilitates sleep at night. However, melatonin is inhibited by artificial light levels with high color-temperature common in Japanese homes at night. In this study, we investigated whether a combination of tryptophan-rich breakfast and light with low color-temperature at night could enhance melatonin secretion and encourage earlier sleep times.MethodsThe intervention included having breakfast with protein- and vitamin B6 - rich foods and exposure to sunlight after breakfast plus exposure to incandescent light (low temperature light) at night (October-November, 2010). The participants were 94 members of a university soccer club, who were divided into 3 groups for the intervention (G1: no intervention; G2: asked to have protein-rich foods such as fermented soybeans and vitamin B6-rich foods such as bananas at breakfast and sunlight exposure after breakfast; G3: the same contents as G2 and incandescent light exposure at night). Salivary melatonin was measured around 11:00 p.m. on the day before the beginning, a mid-point and on the day before the last day a mid-point and on the last day of the 1 month intervention.ResultsIn G3, there was a significantly positive correlation between total hours the participants spent under incandescent light at night and the frequency of feeling sleepy during the last week (p = 0.034). The salivary melatonin concentration of G3 was significantly higher than that of G1 and G2 in combined salivary samplings at the mid-point and on the day before the last day of the 1 month intervention (p = 0.018), whereas no such significant differences were shown on the day just before the start of the intervention (p = 0.63).ConclusionThe combined intervention on breakfast, morning sunlight and evening-lighting seems to be effective for students including athletes to keep higher melatonin secretion at night which seems to induce easy onset of the night sleep and higher quality of sleep.

The Relationship between a Night Usage of Mobile Phone and Sleep Habit and the Circadian Typology of Japanese Students Aged 18 - 30 yrs

“…Exposure to sunlight or lighting by mobile phones in the morning is possible to trigger synthesis of serotonin in the pineal body (Rosenthal et al, 1997;Wada et al, 2013). This action is hypothesized to occur mainly in the morning, because the amount of tryptophan consumed with supper has neither significant effects on Moriningness-Eveningness (M-E) scores nor an effect on sleep habits, as shown by another study on young Japanese children performed in 2005 (Harada et al, 2012).…”

“…Light conditions are most effective zeitgeber for human circadian clock (Wada et al, 2013). Exposure to sunlight or lighting by mobile phones in the morning is possible to trigger synthesis of serotonin in the pineal body (Rosenthal et al, 1997;Wada et al, 2013).…”

Effects of Drinking Cows’ Milk at Breakfast in Promoting Sleep-Health in Japanese University Athletes

“…Morning typed members would be speculated to changed to more-evening typed ones, because the shortage of morning sun lights occurred due to later sun rise in this season of late November and early December. Tryptophan included in the cows' milk could be metabolized to serotonin in the morning and serotonin again would be synthesized to melatonin at night Nakade et al, 2009Nakade et al, , 2012Wada et al, 2013;Harada et al, 2016) in the pineal of brains of the participants. Therefore, the sleep latency seems to become shorter during the intervention due to the melatonin synthesis which has been known as the natural sleep inducer (Bruni et al, 2015) based on the cow milk intake at the breakfast.…”

“…It has been suggested that protein intake at breakfast would raise blood tryptophan levels, and that this would, through the synthesis of serotonin (an anti-depressive agent), be effective in promoting mental health and morning-type habits and also, following synthesis into melatonin, which promotes sleep onset at night (Harada et al, 2007;Nakade et al, 2009Nakade et al, , 2012Wada et al, 2013). For Japanese children, drinking cows' milk at breakfast is an important source of tryptophan and could, on the basis of a questionnaire study (Takeuchi et al, 2014), be supposed to promote the mental and sleep health, although there have been no intervention studies to test this hypothesis.…”

Effects of Reading a Picture Leaflet on Rhythm for Enhancement of Morning-Typed Life in Japanese Infants

“…For example, better mental health can be promoted by the nutritionally rich breakfast (including protein resource as tryptophan supply: Harada et al, 2007;Nakade et al, 2009Nakade et al, , 2012Harada et al, 2012;Wada et al, 2013) based on basic questionnaire studies and intervention studies. On the relationship between the mental health and the frequency to take breakfast in Korea, the data were obtained from the 2013 Korean Community Health Survey; a total of 207,710 survey participants aged 20 years or over were studied.…”