If you’ve ever travelled to a country with a different time zone, you have surely experienced the effects of jet-lag. Jet-lag doesn’t cause many problems if the change in times is just a couple of hours, but some countries have a difference of over six hours, in which case jet-lag can be a real hindrance.
Time zones are a man-made concept, so why do our bodies react in the way they do? Whilst travelling, the body struggles to adapt to an abrupt change in times for light and dark, which heavily disrupts biological clocks. This disruption confuses the body, and jet-lag ensues – you may have trouble sleeping despite being tired, and you may be woken up early.
A team of researchers based in Edinburgh recently published a paper which studied the impact that light has on this clock.
A person’s biological clock is regulated by the suprachiasmatic nucleus (SCN) of the hypothalamus in the brain. The SCN has been known to express vasopressin, but its role was unknown. The team led by Tsuji shows that vasopressin plays a role in the photo-entrainment of biological rhythms. Indeed, vasopressin is released by retinal ganglion cells in response to light and enhances the responses of SCN neurons, telling the body that it is day time.
In a press release, Professor Mike Ludwig claimed that “[their] exciting results show a potentially new pharmacological route to manipulate our internal biological clocks. Studies in the future that alter vasopressin signalling through the eye could lead to developing eye drops to get rid of jet-lag, although we are still a long way off from this.”
Indeed, eye-drops that alter vasopressin signalling could trick the brain into thinking that it is day or night time. Increasing vasopressin signalling in the eyes would lead the brain to think that it is day, whereas inhibition of the pathway would lead it to believe it is night time.
Jet-lag is not the only possible target for this – readjusting the circadian clock could help people who work night shifts, and people who suffer from insomnia. The paper also states that in the long run, a disruption in biological clocks contributes to conditions such as depression, weight gain, metabolic and cardiovascular disorders and increased cancer risk, so understanding how the clock is regulated can help find a treatment for these diseases.