Bed-time food supplements and sleep: effects of different carbohydrate levels.

Blood glucose levels were altered during sleep by means of manipulating carbohydrate (CHO) intake through bed-time food supplements. Protein and fat intake were minimally affected. Subjects underwent all conditions in a balanced designed. A high CHO condition resulted in significantly reduced stages 1 + 0 sleep over the whole night and significantly increased REM sleep during the first half of the night; there seemed to be a reciprocity between these two changes. High CHO also produced a whole-night significant decrease in stages 4 sleep, which persisted into the recovery night. Few significant differences between the other conditions of low and zero CHO were found. Sleep onset was not affected. It was concluded that relatively high blood glucose levels were required to alter sleep, and perhaps lead to more 'restful' sleep. The present findings were similar to those of related studies. The REM sleep changes were discussed in relation to increases in brain serotonin synthesis mediated by elevated blood glucose levels.