Research in the Proceedings of the National Academy of Sciences (PNAS), suggests that the cells' power plants - the mitochondria - are highly regulated by the body's biological, or circadian, clocks. This may help explain why people who sleep and eat out of phase with their circadian clocks are at higher risk of developing obesity, diabetes and metabolic syndrome.
They looked for circadian changes in the mitochondria that, by creating peaks and dips in the cells' energy levels, would also help regulate their day-night cycles. The group identified and quantified hundreds of mitochondrial proteins, finding that the quantities of a whopping 40% peak once a day.
Further research identified the proteins making up the mitochondrial circadian clock that regulates these activities. Surprisingly, most of the circadian proteins in the mitochondria peaked four hours into the daylight part of the cycle (in mice, which are active at night).
To check, the researchers provided mitochondria with sugar and found that at around hour four, respiration and glucose utilization were indeed at their highest. They also found that the protein responsible for the entry of fatty acids into the mitochondria only peaks at the eighteenth hour and, again, tests showed fat processing was optimal at the same time.