How Circadian Rhythm Affects Health
Are you in rhythm with yourself? The latest research has shown how your internal rhythm affects health, all the way down to the molecular level.
In recent years we have gained more and more knowledge about our inner biological rhythm. In the brain there is an area (the suprachiasmatic nucleus) that serves as a conductor for the body’s 24-hour rhythm, the circadian rhythm.
This in turn controls clock genes in various organs, which makes insulin production, uptake of sugar and fat metabolism change in synchrony during the day and night. The body functions like a well-tuned orchestra.1
But sometimes our personal habits become like musical marauders. The conductor loses the beat. The individual organs come out of sync. The orchestra starts to play out of tune.
It is estimated that 15-20% of the population have shift work. Many people travel across time zones for work or in their free time. Numerous people have chronic sleep problems. This upsets our internal rhythm, which increases the risk of obesity, heart disease, and also certain forms of cancer.2
The Circadian Rhythm Affects Health
But even milder disturbances to the circadian rhythm can lead to problems. A different rhythm on weekends than on weekdays (so-called “social jetlag”) or strong lamplight in the evening after the sun has gone down can be enough to influence the internal clock.
And by the way, did you know that the number of heart attacks increases in connection with the reset from standard time to daylight savings time? 3
A disturbed internal clock can also contribute to type 2 diabetes. Conversely, diabetes means in turn that the body’s organs get even more out of sync, through reduced sensitivity for insulin and other causes.
The disturbance in the clock can even predict complications. Diabetes patients for example run an increased risk of heart disease if the natural lowering of blood pressure at night has disappeared.
The Inner Clock and Our Eating Habits
The connection between the internal clock and metabolism matters for how we should eat. In a dieting study with 420 overweight individuals, the persons who ate late in the evening had less weight reduction than those who ate most of their food earlier in the day, even if in total they ate the same amount.
Other studies have shown that persons who eat most of their food in the evening have worse blood sugar values. This is due in part to the fact that insulin sensitivity and insulin production have a natural 24-hour rhythm. Our systems for taking care of food simply don't work as well in the evening.
Advice for Rhythm
A disturbed inner clock certainly contributes to more cases of disease than we think. But with small means we can do a lot to restore the rhythm. Here are some tips:
1. Try to the greatest degree possible to keep the same rhythm every day, even on weekends.
2. Try to get a lot of light during the day, preferably within 2 hours from when you get up, and minimize artificial light, e.g. strong lamps, late in the evening.
3. Cut down on evening snacks – and don’t eat much at all late in the evening.
4. Follow your biological clock as far as is practically possible – some people have a natural rhythm that is shorter than 24 hours (typical “early birds”) and others a longer one (“night owls”).
5. Interrupted sleep or poor sleep quality can disturb the biological clock. Avoiding coffee, tea, Coca-Cola and chocolate in the evening, keeping the bedroom dark and cool, avoiding long naps during the day, turning the clock away so that you can’t see the time if you wake up in the middle of the night, or finding a relaxing ritual before going to bed, are examples of measures that facilitate good sleep.
6. Sleep apnea syndrome, often with breathing interruptions and snoring, is more common with obesity and diseases such as type 2 diabetes. It can produce interrupted sleep, nocturnal sweating, and a sense of never being rested. There may be many different reasons for these symptoms, but investigation through medical care may show whether you need treatment.
7. Regular daily exercise (however not too late in the evening) is one of the best sleeping medications.
8. Exercises in relaxation and mindfulness, which are found on these pages and in a number of other contexts, can help you get a good rhythm.
We often treat our body as if it were a hard-driving rock band. In reality it is a sensitive symphony orchestra.
How can you listen more to your inner rhythm?
- Qian J et al., Circadian System and Glucose Metabolism: Implications for Physiology and Disease. Trends in Endocrinology & Metabolism, 2016, Vol. 27, No. 5
- Bass J et al., Circadian Integration of Metabolism and Energetics. Science Dec 2010
- Maury E et al., Review: Circadian disruption in the pathogenesis of metabolic syndrome. Diabetes & Metabolism 2014. 40:338–346