Lights Out

Patricia Lakin-Thomas has spent her scientific career – first at the University of Cambridge, in the U.K., and, since 2002, as a professor of biology at York – probing a question that lies at the nexus of biology, astronomy and even philosophy: why do living things need internal clocks that are finely tuned to the cycle of day and night?

The key lies within an intriguing fungus called Neurospora crassa, a focal point of Lakin-Thomas’s research as the head of York’s Clocklab. A unique York scholarly initiative, the lab specializes in investigating the biological clocks of various organisms, shedding light on their intricate mechanisms.

The Neurospora organism – sometimes found on old bread – is neither a pathogen nor a yeast. Its role in the grand scheme of things is to digest the charred matter in the wake of a forest fire. As Lakin-Thomas explains, “it doesn’t attack live plants. It certainly doesn’t attack people. It just is one of those wonderful organisms that clears away dead stuff in the environment.”

Organisms that are in sync with the light/dark cycle survive and compete better than those that are out of sync with it

Neurospora, as it turns out, also has a biological clock, a bit like the circadian system that makes us sleepy at night and wakeful during the day. This fungus tends to build up proteins at night and throw off spores – a highly energy-intensive process – after dawn, so it can propagate. 

In the plant world, the environmental differences between day and night are huge, due to the heat and energy of the sun. Plants need the cooler temperatures and the lack of light to prepare themselves for the process of photosynthesis that takes place during the day.

“We can show from some simple lab experiments that organisms that are in sync with the light/dark cycle survive and compete better than those that are out of sync with it,” Lakin-Thomas says. 

Shift work has actually been declared a potential carcinogen by the World Health Organization

In other words, the evolutionary advantage goes to organisms that pay attention to their bedtimes, with a few exceptions, such as cave-dwelling crabs and fish.

As Lakin-Thomas points out, there’s now a significant body of empirical evidence to show that poor sleep is associated with cardiovascular diseases, obesity and other chronic conditions. 

“In particular, we’ve got lots of research on the declining health of shift workers. Shift work has actually been declared a potential carcinogen by the World Health Organization,” she says.

While her work is in pure science, Lakin-Thomas has recently begun to dedicate more of her research energy to the habits of contemporary society – daylight saving time, late-night scrolling on a smartphone – that disrupt rhythms that have been literally programmed into our DNA for millions of years.  

The genes linked to the internal clocks of Neurospora, she has discovered, can also be found in cells that produce various proteins linked to metabolism – a connection that helps explain why we’re more susceptible to weight gain from eating late at night.

“We keep telling people, as part of your sleep hygiene, to get a good night’s sleep and to get your circadian clock well organized with the day,” Lakin-Thomas says. “Try to get up at sunrise and then keep those blue screens away from you at night.”  ■