For several decades, scientists have been accumulating knowledge about circadian rhythms, the daily ups and downs of our metabolic processes. Only recently, however, have they returned to the time honored concept of chronotherapy to help people get well.
Different organs seem to operate on different time sequences. These functions are so regular that medical writer Dunja Voos deems them "clockwork organs." Scientists believe that we have genetically determined clocks that operate many of our hormonal functions, including the secretion of insulin and cortisol, as well as mechanisms that respond to changes in the season, changes in lighting, and changes in our daily activities. Knowing when your body is likely to focus on a particular symptom makes it easier to treat the symptoms of disease.
Knowing when to take a pain reliever in anticipation of a severe headache can make a huge difference in the severity of the subsequent pain. Different kinds of headaches, however, occur at different times of day. Cluster headaches, for example, typically strike during REM sleep, sometime between midnight and three in the morning. If you tend to have cluster headaches, your doctor may advise you to give your child (cluster headaches are most commonly a problem of children) a pain reliever just before you go to bed.
Migraine headaches tend to strike first thing in the morning, around sunup. At least you can have your treatments handy for early morning use, even if you can't get up in the middle of the night to take them. Men who get migraines tend to experience their symptoms later in the day than women, closer to mid-morning.
Redness in the eyes is usually worst early in the morning. This is the time pinkeye and conjunctivitis symptoms will be most severe. Dry eyes (caused by conjunctivitis sicca or autoimmune diseases such as Sjogren's syndrome) will tend to be worse later in the day. Using eye drops in the late morning maximizes their effectiveness.
Even Cardiac Arrhythmia Has A Rhythm
Emergency room doctors notice that sudden death, the heart suddenly stopping, is most likely to occur between six in the morning and noon. Heart pain with an EKG signature of a raised ST segment, however, is more common between six in the evening and midnight. Sudden death in insulin-dependent diabetics, however, occurs almost exclusively during sleep.
Chronic heart conditions like congestive heart failure typically get worse during the day and, if they are going to cause a need for emergency treatment, become critical at night. Heart attack (myocardial infarction), nowever, usually occurs during the day, except among people who take a medication in the beta-blocker class to control their heart rhythms.
High and low blood pressure also seem to cycle during the day. During sleep, blood pressure levels are 10 to 25 percent lower than during the day. Both systolic and diastolic blood pressures increase after waking in the morning. As people get "revved up" for their daily activities, especially if they have to exert physical effort under time pressure (running to catch a bus, hurrying to go to an appointment), blood pressure levels reach their peak. This is the reason the blood pressure measurement your doctor takes late in the morning, especially when you had to rush to make the appointment, can be uncharacteristically high.