Michael W Young feels the effects on his body whenever he spends time in Manhattan. Though his research team is based in New York, at Rockefeller University, Young lives outside the city and is accustomed to gentler surroundings. On his trips into town, he’s keenly aware of the unceasing lights and traffic noise.
This isn’t just personal. Together with Michael Rosbach and Jeffrey C Hall, Young won the 2017 Nobel Prize in Physiology or Medicine for pioneering research into circadian rhythms, including the identification of the clock genes that regulate so much of our daily behaviour.
Light is one of the key zeitgebers, or timekeepers, that keep our internal clocks attuned to the outside environment. And light pollution is a major reason why, according to Young, “big cities are an impediment to the inner clock”. Too much or too little light can send our natural cycles off-kilter.
Does this matter? Being off-cycle has been linked to health problems, including the insomnia that’s symptomatic of circadian-rhythm sleep disorders (affecting people whose body clocks are set to unusual hours) and shift-work sleep disorder (affecting people who work during non-standard hours). Circadian misalignment has been linked with obesity, cardiovascular disease and psychiatric disorders. This shows how critical circadian rhythms are to maintain healthy metabolism, sleeping patterns and moods.
As Young says, “Our bodies work best when there is agreement between all these signals.” And the signals are disrupted by cities.