Can Circadian Clocks Help Us Adapt to Climate Change?

You asked; Dr. Steve Kay, the dean of USC Dornsife and one of the foremost experts in understanding how plants and animals process the natural cycle of night and day, answered.

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Now, drum roll (or alarm clock) please:

1. On plants and animals, from Lily Layman and Jaycey Chavez: Do animals have the same circadian rhythm as plants, and if so, does this mean animals could go through the “genetic switch” and adapt better to climate change? Along those same lines, do peoples’ circadian rhythms react similarly to circadian rhythms found in plants in the sense they can be changed by temperature?

There are many similarities between animal and plant clocks—they can both be reset by light and temperature, they regulate a wide range of processes, and the clocks persist in constant conditions. Although clocks can help animals and plants to optimally adapt to the diurnal cycles generated by the rotation of the Earth, climate change is occurring very quickly, so it is not clear if having a clock allows an organism to adapt better. However, understanding how clocks are linked to temperature-regulated processes may help us find strategies for the breeding or design of crop plants that can give sufficient yields under the more stressful conditions that are likely to be produced by climate change.

2. On the diversity of circadian rhythms, from Morgan K., Parker P., and Charlotte Rice: How long does it take for someone to build up a circadian rhythm and do circadian rhythms work the same way in everyone? For example, some people work night shifts at work, which means their circadian rhythm is opposite of most of ours. How long would it take for them to go back to “normal”? Ultimately, what’s the best way to change your circadian rhythm? 

Babies are thought to develop circadian control of sleep wake cycles around 4-6 months of age. Certainly all the key properties of a circadian clock do work the same for everyone, except some people who may be carrying mutations in circadian rhythm genes. If you work night shifts, your clock can be quite disturbed, and this is thought to underlie the higher risk for chronic diseases seen in night shift workers such as breast cancer and cardiometabolic diseases. Our clock, which regulates the sleep wake cycle, can usually be “bumped” to the new light dark cycle a person experiences in 2-3 days. The best way to change your circadian rhythm is to expose yourself to bright light at dawn or dusk in your new time zone.

3. On teenagers and early waking times, from Libby Underwood and Garret Husslage: How can high school students use your expertise on circadian rhythms to be able to wake up easily in the morning? Many people say that teenagers need more sleep and should start school later—is that more of a mental positive to wake up at a later time or can you adjust the circadian rhythm to positively impact waking up at an earlier time?

As adolescents go through puberty, their clocks shift later, which is why so many teenagers show a preference to go to bed later and wake up later. This doesn’t necessarily mean that teenagers need more sleep; they are just shifted later than their parents. Past puberty, our clocks slowly drift earlier and earlier as we age. Some chronobiologists have argued for later start time in schools, but this is going to be very expensive to implement on large scale. I suggest avoiding screens in the middle to late evening before you go to sleep. A recent study shows that the blue light from tablet devices can cause significant sleep disruption.

Image Credit:  Musée de l’horlogerie from Flickr