The bad news: biorhythm calculations are about as informative as coffee grounds. The good: biological rhythm exists. Over the course of its evolution, humans developed an internal clock that, seen over the span of a day, adjusted to the change between light and dark.
Our internal clock
Over thousands of years, the day-night rhythm set by the sun has become fixed in the genes; in every cell there are such “clock genes” that control the daily sequence of bodily functions. Temperature, pulse, pain perception, mental and physical performance, activity of kidneys, liver and digestive system, almost all processes in the body tick in time with these ancient biological timers. There are the well-known morning grouches and early risers, but despite individual deviations in the day-night rhythm: Very few people are completely “nocturnal” by nature. Most night workers struggle against their inner clock. The constant drifting apart between biologically predetermined rest and forced activity means that night and shift workers suffer more frequently from depression, gastrointestinal and cardiovascular problems. Every now and then, however, “night work” also has its positive sides: Most children are born at night – provided you let them.
Nature runs leisurely
If you give the inner clock free rein by removing external influences such as the alternation of light and darkness and social constraints, it usually runs a little slower and settles down to a 25-hour day. This is why the daily rhythm is called “circadian” (from “circa” and “this,” the day). Scientists have now also discovered where the human “central clock” is located: it is an organ the size of a grain of rice in the brain, which is connected to the eyes by nerve tracts that are different from the optic nerves. This is why blind people also live in a day-night rhythm. Only when their ocular nerves are completely missing, for example due to an operation, do they lose their sense of time. Diseases also follow a certain daily rhythm. Most heart attacks happen in the morning between eight and twelve o’clock, rheumatics usually suffer most from stiffness and pain in the morning. And it’s best to go to the dentist in the afternoon. For one thing, the sensation of pain is weakest around 3 p.m., and for another, local painkillers and anesthetics take the longest to work at this time.
Save on medications, reduce side effects
It is precisely these cycles that chronopharmacologists (chronos = time) are trying to explore more closely in order to achieve the best possible effect of drugs or to reduce side effects. For example, Björn Lemmer, professor of pharmacology and toxicology, says: “Not only does the right amount of the right substance have to reach the right target organ, this also has to happen at the right time,” a classic example, he says, is the drug theophylline for asthma. “Here, a drug has been approved that can save patients from having to take it three times a day. It only has to be taken twice, a weaker dose in the morning and a stronger dose in the evening. Or just a strong evening dose, because asthma attacks are more likely to occur at night than during the day anyway.” One example of how the right timing improves efficacy and tolerability is pain-relieving drugs prescribed for rheumatism. If patients take the medication in the evening, they tolerate it better and at the same time the active ingredient is available when they need it most, namely in the morning. Incorporating biological rhythms into treatment may not cure a disease faster or better, but it can at least make life easier for the patient.
A matter of time
For some medications, it is now well established scientifically whether their effectiveness follows biological rhythms and, if so, when they work best or are best tolerated. Individual deviations from the average daily rhythm need not be considered. However, it has not yet been researched whether different rules apply to people whose work rhythm deviates greatly from the biological rhythm, e.g. shift workers, stewardesses, pilots. Taking in the evening
- Mequitazine, a certain antihistamine against allergies.
- H2 blockers, such as cimetidine, famotidine and ranitidine, to lower stomach acid in gastric and intestinal ulcers
- Statins, such as simvastatin and lovastatin, to lower cholesterol.
- Painkillers and anti-inflammatory agents, known as NSAIDs, such as acetylsalicylic acid, ibuprofen and ketoprofen.
- Theophylline, salbutamol and prednisone for asthma, although here usually still a smaller dose in the morning is necessary
Taking in the morning
- The beta-receptor blocker propranolol in angina pectoris.
- Proton pump inhibitors, such as omeprazole, which also curb stomach acid but act differently than H2 receptor inhibitors. They are prescribed for both gastric and duodenal ulcers, as well as chronic heartburn
- Glucocorticoids in rheumatism
Taking in the afternoon
- Local painkillers and anesthetics
- Hepatitis B vaccination
