Question: If an animal was kept in a dark room from birth with a constant temperature from birth, and it was then taken out into its natural habitat, would it have a functioning body clock? How would this effect them? (I appreciate that this would be cruel and am not planning to do it!)

Indi Ghangrekar answered on 19 Mar 2012:

What an excellent question jammiedodger!! You’ve obviously thought through lots of variables that would affect the body clock, this is a very scientific question!

The great thing about the body clock is that it continues to function even if an animal is raised in constant light or dark at a constant temperature, the body clock continues to function. In this situation it means that instead of an animal having a 24 hour activity rhythm, it has roughly 24 hours give or take an hour either way and there can be some variation between individuals. This is why body clock research is called circadian rhythm research – circadian is from Latin circa diem meaning about a day – so research on rhythms that need about a day or so to complete a cycle.

In addition to being a clock mechanism that goes round in cycles and is self-sustaining, the body clock also allows input from environmental conditions like temperature and light. The way that light information gets sent to the body clock in mammals is through the eyes where a small specialised set of cells detects light and has a direct connection to the body clock to inform that light is present. This connection will still be able to send information to the body clock that light is present and, in the natural environment, light information will have a daily rhythm and the animal will therefore still have a functional daily rhythm that will now be closer to 24 hours due to Earth’s rotation on its axis being 24 hours.

However, because the postnatal development of the animal will be affected due to the lack of light, there will be changes compared to an animal that has always been in the natural environment. There will be greater sensitivity to light for example. If a similar experiment was done raising the animal in constant light, you’d also see similar results – they’ll still have a body clock but the development will be affected. The differences in behaviour between the 2 different groups of constant light, constant dark plus the control group raised in normal conditions would have to be monitored in normal conditions but also by testing the response to constant dark or constant light to understand the what the effect has been on development.

You’ve hit upon a huge topic here and I hope I have been able to be clear enough in my very short answer to it! Let me know if you have further questions about it! 🙂