It’s very rare for me to be actually awakened by an alarm clock. Generally I wake up on my own just a few minutes before the alarm is set to go off–which is actually kind of annoying, since mornings when I have to set an alarm to get up are invariably mornings when I want to get all the sleep I can.
The reason I wake up before the alarm is that I have an additional clock, not on my bedside table, but in my head. And I’m not alone. The fact is, we each have an internal clock, even those for whom the alarm always comes as an unwelcome intrusion into a pleasant dream. Our bodies need that internal clock to regulate a number of bodily functions, of which sleep is only the most obvious.
For years, researchers have though that our biological clock was entirely in our heads, based in a region of the brain called the superchiasmatic nucleus. But a recent study published in the journal science indicates that in fact the clock may be spread out throughout our bodies, so that not only our heads, but also our legs, abdomens and just about everything else are involved in keeping us on a regular 24-hour cycle.
The study published in Science wasn’t actually conducted on humans–it was conducted on fruit flies and fireflies. Steve Kay, a cell biologist at the Scripps Research Institute in San Diego, was studying a gene called the period gene. It’s this gene that turns some cells into biological clocks.
He used a fluorescent green dye to track the locations where the period genes showed up in the fruit flies–and found that it was everywhere: in the digestive tract, on the feet and legs, and at the base of tiny hairs. Further testing on firefly genes showed that these clocks were ticking away in a nice, regular, 24-hour rhythm. Kay also discovered that all of these clocks, no matter where they were located, could be reset with light. That indicates two possibilities: one, the cells where period genes are located could also have heretofore undetected light receptors, and two, it could be that light, not the brain, is what really controls our body clocks.
Applying these findings to humans doesn’t require as great a leap of logic as it might seem: we already know that the period gene is found in humans and other higher mammals. We even have a hint of where the gene is most prominent in humans (at least, male humans): tests have shown that in mice, the gene shows up the most in the testes. The same could be true of us.
Better knowledge about how our biological clocks work could have many beneficial spin-offs. If we can learn to reset these period gene-run clocks, we could develop new therapies for seasonal-affective disorder (’tis the season for that, all right!), jet lag and sleep problems in shift workers.
It might have other medical benefits, as well, because it’s not just sleep that’s governed by our internal clock. Our entire body undergoes significant internal changes as day turns to night and back to day again. Blood pressure is a good example. It isn’t constant: it normally rises in the morning (in expectation of increased physical activity), remains elevated during the day and early evening, and then decreases to its lowest level during sleep.
These kinds of changes are particularly significant to people suffering from various diseases, because the changes their bodies go through in response to the ticking of their internal clocks influences their symptoms. For example, hay fever sufferers find that the symptoms of sneezing and runny or stuffy nose tend to be worse in the early waking hours. Asthma symptoms are more than 100 times as likely to occur in the last few hours of sleep than during the day. Angina is most common in during the first four to six hours after awaking, as are heart attack and stroke. Rheumatoid arthritis suffers usually find their symptoms most intense upon awakening; osteoarthritis suffers usally find their symptoms worsening in the afternoon and evening. Ulcers sometimes act up early in the morning, disrupting sleep, and epileptic seizures, in many people, often occur only at particular times of the day or night.
As a result, our body clocks can even influence how we perform on medical tests, and the resulting diagnosis. More and more doctors are aware of this, and try to monitor symptoms over a 24-hour period or to run tests at several different times to get a truer picture of the condition they’re diagnosing.
Increasingly, this kind of thinking is being applied to drug therapy, as well. If the symptoms of your asthma are worse at night, then maybe you should be taking your pill just before bedtime instead of first thing in the morning. Since osteoarthritis tends to worsen in the afternoon and evening, some doctors recommend taking medication for it at mid-day. Antihistamines, anticancer drugs, corticosteroids–the effective of many drugs can be enhanced if they’re taken at a specific time of the day, a time that may vary from patient to patient depending on their own internal clocks.
The more we understand about our body clocks and the they bodily cycles they regulate, the better we may be able to treat a whole host of diseases and conditions, enhancing the lives of many people.
Who knows? Maybe we’ll even figure out a way to keep our internal clocks from ringing alarms in our head on the weekend, waking us up at our usual weekday getting-up time on the one day of the week we get to sleep in.
Now THAT would be a scientific breakthrough worth celebrating!
