Northeastern University College of Science

Dear College of Science Faculty and Staff,
 
One time, I was in London visiting my dear cousin Jane, and set my alarm to make an Amsterdam flight next day for a conference around Xenopus (frogs). On waking, I was puzzled to see that the times on my wristwatch and phone were different. Maybe the battery in my watch needed replacing? Jane was still asleep, but I thought the phone must be correct, and hurried to the airport. Later, I learned that the UK also has daylight saving time, and I happened to visit right over the change. Who knew?
 
There’s concern that daylight saving time changes are bad for us. The concern has fascinating underlying science, as old as life on earth, that has to do with ‘circadian rhythms’. Circadian rhythms are changes in your body functions across day and night, that include sleeping and eating patterns, body temperature, brain activity, hormone production and cell regeneration. Cyclical changes are present in almost everything living – animals, plants and microbes. Even very ancient lifeforms, cyanobacteria, show changes across the day/night cycle, connecting to geological time, to the earth’s 24-hour rotation that gives day and night, and possibly to earth’s chemical conditions billions of years ago.
 
Your circadian rhythms can be re-set to some extent, as when the seasons and day length gradually change, when you cross time zones through travel, and with daylight savings time. Jet lag results from your body thinking it is one time of day, when suddenly you’re getting cues that it’s another time. Jet lag goes away as your body resets to the new day/night timing. But in fact, circadian rhythms are so deeply ingrained, that even without light/dark cues (eg living in total darkness) our cyclical body functions continue! They continue with slightly altered timing called the free running period (FRP). It’s complicated to measure this, but for animals active during the day like most of us, the FRP is around 25 hours.
 
So, how does your body control your cyclical rhythms? This is done by amazing ‘biological clocks’, which like all clocks, monitor the time. Almost every tissue or organ in your body contains a biological clock, and all of these are synchronized by a powerful leader clock in part of the brain called the suprachiasmatic nucleus. The clock mechanism, whose discovery led to a Nobel Prize, has to do with sets of genes and the proteins they encode. The general idea is that over the course of the day, the amounts of clock proteins build up to a peak, at which point a ‘feedback’ process is triggered that leads to their destruction. The cycle then starts again, with clock proteins being made, reaching a peak, destroyed, made, destroyed with a periodicity that mirrors day and night, and controls the cyclical changes of your body.
 
Now that we are in the early-night, short day, part of the year, mostly due to the changing season, and a little bit due to daylight savings time, your body is expertly adjusting its clocks and circadian rhythms. Please take care of yourselves in this changing season, and in these troubled times.
 
Thank you for an excellent COS Community Meeting yesterday, Nov. 9. slides are posted. Warmest wishes.