Food could be a new weapon in shaking off the effects of jet lag after research in mice showed that the insulin released as a result of eating can be a key factor in restoring a disrupted body clock.
Miho Sato and her colleagues at The Research Institute for Time Studies
at Yamaguchi University in Japan did experiments in mice and tissue cultures to show, for the first time, that increases in insulin affect circadian rhythms
. These daily rhythms affect alertness, sleep patterns, and mediate many other physiological processes.
Your biological clock is regulated by two broad factors: first, the central rhythm is reset daily by light, as sensory input from the eyes is processed by a small part of the brain called the suprachiasmatic nucleus.
The rise and fall of hormones linked to sleep, for example, match this rhythm. But circadian rhythms are also present in peripheral "clocks" in a wide range of cell types in the body. Some of these can be influenced by food.
Sato demonstrated the role of insulin by shifting the peripheral body clock in the livers of mice by feeding them only at night. They then split the mice into two groups, supressed insulin levels in one group, and returned all the mice to daytime feeding. Four days later, the livers of the non-supressed mice had readjusted to a normal daily rhythm, as revealed by the daily rise and fall of liver-gene expression. The livers of the insulin-suppressed mice had still not returned to normal.