It has always been a puzzle as to why the main body clock doesn’t reset itself more quickly when you travel. After all the SCN (suprachiasmatic nucleus – the master clock) does use light signals to help entrain biological rhythms. Researchers at Oxford University think they have found an answer (Jagannath et al., 2013).
First of all, it does make sense, for the SCN to have an inbuilt tendency to resist being too responsive to light otherwise it could be affected by the moon or indeed by street lighting and in fact lighting generally. So it’s not surprising that there is an inbuilt brake in the form of a gene called SIK1. When the SCN is exposed to light a number of genes start resetting the clock but, apparently, SIK1 goes around switching them off (in mice at least). If SIK1 is blocked, resetting is almost twice as fast.
And there may be some implications for other disorders, such as schizophrenia. The same team conducting the research with SIK1 has also investigated disruption of circadian rhythms in people with schizophrenia and other mental disorders where sleep disruption is common. In these conditions the fact that the SCN appears to be out of phase with other body clocks may be significant, and SIK1 may be used to resynchronise the body’s clocks.