Your Body's Internal Clock and How It Affects Your Overall Health Not getting enough sleep leaves us tired during the day. But research has been finding that the body's clock is responsible for more than just sleep and wakefulness. Other systems, like hunger, mental alertness, and mood, stress, heart function, and immunity also operate on a daily rhythm. We're beginning to understand more about how the clock interacts with and helps govern the function of other systems and affects our overall health. In fact, keeping your body's daily cycle on an even keel may be one of the best things you can do for your overall health. ENVIRONMENTAL DISRUPTIONS TO THE BODY'S CLOCK Some of the best knowledge we have about the roles the biological clock plays in our health come from instances in which the cycle gets out of sync . This can happen for different reasons, and we're just starting to understand them in greater detail. Sometimes we do things ourselves that disrupt our normal rhythms, like flying to a distant time zone. Sometimes it's other factors, (like genes or biology) that play a role. Jet Lag Flying across the country on the red-eye is a prime example of how we can disrupt our own clocks, and a far more extreme example than the spring forward/fall back ritual in many parts of the U.S. When jet lag sets in, we feel disoriented, foggy, and sleepy at the wrong times of day because, after changing time zones, our body clock tells us it's one time and the outside environment tells us it's another. In fact, jet lag can be considered one type of circadian rhythm disorder. It can be treated simply be allowing the body to adjust to the new time, although it may take several days for external cues (light) to help the internal clock catch up or fall back with its new cycle. BIOLOGICAL AND GENETIC DISRUPTIONS AND THEIR IMPLICATIONS FOR HEALTH The interactions of the clock are complex, and their effects on different body systems are intricate, but we're starting to understand more about how the nuts and bolts of the clock work, and affect each system of the body, from our hearts to our moods. Since the biological clock is, in fact, a biological entity, things can go wrong with it that may have less to do with lifestyle or the environment, and more to do with the mechanisms of the clock itself. For example, there's more to the clock-diabetes link than just turning our sleep cycle around, though sleep can make a difference. The Rhythms of the Heart The heart is one organ that, although it can keep time by itself to some degree, relies on the brain's biological clock for cues. For years doctors and researchers have noticed that heart problems like fatal arrhythmias (心率失常) are more likely to occur at certain times of the day, both in the early morning and to a lesser degree, in the evening hours. Taking blood pressure medication in the evening seems to improve its effectiveness because it works with the body's circadian rhythms. Immunity and Vaccinations Most of us have experienced being more susceptible to getting sick when sleep-deprived. The reason for this appears to be that certain chemicals responsible for immune function, like cytokines, wax and wane throughout the day and sleep deprivation deprives us of their best effects. Animals who are given vaccines at specific times of the day, when certain proteins that sense bacterial invaders are highest, have a much stronger immune response, even weeks later. The same is very likely true for humans. Body rhythms don't just enhance vaccines' ability to provide immunity; they can affect the body's ability to battle infection on its own. When mice were exposed to a bacterial infection, the severity of their infection reflected the time of day they were infected. It's not just in the lab that these effects are seen. Babies who are given vaccines in the afternoon — and who sleep more right after — have better immune responses to the innoculations. It's likely that the same effect is true in adults, since our immune systems fluctuate in similar ways. Rhythm and Moods Our internal clocks also have a hand in whether we feel up or down emotionally. People with mood disorders like depression, bipolar disorder (躁郁症) , and seasonal affective disorder (SAD) have altered circadian rhythms. In fact, sleep disturbances, both sleeping too much and too little, are one of the key symptoms of depression and other mood disorders. The circadian rhythm-mental health connection has also been linked to disease states like Alzheimer's, Parkinson's, and Huntington's, and even autism spectrum disorder. Researchers are finding that disrupted daily rhythms can be good predictors for the development of mild cognitive impairment that comes with age, and even for dementia.