Spending time with circadian rhythms
By Alexander Michels, PhD August 11, 2014
Research at the Linus Pauling Institute has found that lipoic acid, a substance found in many plants and animals and also made in the body, modulates circadian rhythms in laboratory rodents. We realize that circadian rhythms aren’t something you hear about every day, so here is a primer on circadian rhythms and their importance.
The concept of biological clocks
We all know that human behavior is influenced by clocks. We consult alarm clocks, computer clocks, and phone clocks to set up a schedule of daily activities that need to happen at particular times. Often we establish daily timed patterns of activities, get accustomed to those patterns, and notice when changes disrupt our routine.
In a very similar way, our bodies have internal clocks to time certain physiological events. We are not conscious of many of these changes, such as alterations in blood flow, body temperature, or hormone production. But we do feel some of the results, for example, being tired or hungry at particular times of the day.
By Alexander Michels, PhD August 11, 2014
Research at the Linus Pauling Institute has found that lipoic acid, a substance found in many plants and animals and also made in the body, modulates circadian rhythms in laboratory rodents. We realize that circadian rhythms aren’t something you hear about every day, so here is a primer on circadian rhythms and their importance.
The concept of biological clocks
We all know that human behavior is influenced by clocks. We consult alarm clocks, computer clocks, and phone clocks to set up a schedule of daily activities that need to happen at particular times. Often we establish daily timed patterns of activities, get accustomed to those patterns, and notice when changes disrupt our routine.
In a very similar way, our bodies have internal clocks to time certain physiological events. We are not conscious of many of these changes, such as alterations in blood flow, body temperature, or hormone production. But we do feel some of the results, for example, being tired or hungry at particular times of the day.
Biological clocks ‘run’ or are regulated by molecular interactions. Many clocks are running in your body at any particular time, and most of these clocks are self-regulating and cyclical, each running for a different period of time before they are ‘reset.’ One clock, known as a circadian clock (from the Latin circa meaning “about” and dies meaning “day”), maintains your body on a cycle of about 24 hours.
However, don’t confuse a circadian clock with a circadian rhythm. The rhythm is the output from the cycle generated by the clock. Just as we determine when to go to work based on the time displayed on a physical clock, our bodies determine when it is important to increase the expression of certain genes or signaling molecules based on the timing of the circadian clock.
And since the clock cycles throughout the day, so do these signals – they are stronger at certain times of the day and weaker at other times. It is this circadian rhythm that has a great influence on our bodily functions.
Many people fail to realize the significant impact of circadian rhythms in life. It is estimated that at least one-third of all genes in our bodies are affected by the circadian clock, and maintaining circadian rhythm is important to keep ourselves synchronized with our environments and in good health.
Resetting the circadian clock
Our bodies have a critical feature built into the circadian clock: it can be ‘entrained.’ In other words, the body has molecular ‘sensors’ that can set patterns of gene expression. After receiving input from these sensors (sunlight is a good signal to set our clocks), the body uses molecular switches to adjust the timing of our internal clock with our surroundings. When the circadian clock becomes shifted, it can, in turn, change circadian rhythms and adapt body responses to environmental changes.
Circadian rhythm and disruption
A good example of circadian clock disruption is jet lag. When you take a long flight over multiple time zones your body’s sleep cycle becomes desynchronized from the environment. Gradually, your sleep patterns become regular again – learning from the cues of your surroundings.
What happens if we don’t return to normal, if the entrainment doesn’t have time to adapt due to constant disruptions, or if the clock and the rhythm are out of sync for different reasons? In general, this is considered a bad thing as it increases the risk for many chronic diseases.
Circadian rhythms are often disrupted in older individuals, and this disruption can affect many aspects of cellular function (metabolism, repair, stress resistance, inflammation, and proliferation), although it is not yet clear why this occurs. Many researchers believe that this disruption may increase risk for chronic disease in older individuals.
Is there anything we can do about this age-related disruption?
Potential regulators of the clock
Scientists at the Linus Pauling Institute have recently found that giving lipoic acid, a compound essential for cellular metabolism, to rodents helped to restore age-related changes in the circadian rhythms in the liver. The liver has a special circadian clock, one that can be entrained by lipoic acid. This effect of lipoic acid on the liver could help explain many of its observed effects on metabolism.
Lipoic-acidLipoic acid supplementation has previously been shown to enhance physical activity and memory in old animals and older adults, but it is unclear if these changes are all attributable to changes in the circadian clock. It is also unknown whether lipoic acid can affect circadian rhythms in other organs besides the liver.
Further research is needed to determine if lipoic acid supplementation can effectively modulate circadian rhythms in humans and what the optimal supplemental intakes might be to improve overall health.
For more information on the effects of lipoic acid on circadian rhythms, also see this study from the Linus Pauling Institute:
And for more information on lipoic acid, see the Micronutrient Information Center.
However, don’t confuse a circadian clock with a circadian rhythm. The rhythm is the output from the cycle generated by the clock. Just as we determine when to go to work based on the time displayed on a physical clock, our bodies determine when it is important to increase the expression of certain genes or signaling molecules based on the timing of the circadian clock.
And since the clock cycles throughout the day, so do these signals – they are stronger at certain times of the day and weaker at other times. It is this circadian rhythm that has a great influence on our bodily functions.
Many people fail to realize the significant impact of circadian rhythms in life. It is estimated that at least one-third of all genes in our bodies are affected by the circadian clock, and maintaining circadian rhythm is important to keep ourselves synchronized with our environments and in good health.
Resetting the circadian clock
Our bodies have a critical feature built into the circadian clock: it can be ‘entrained.’ In other words, the body has molecular ‘sensors’ that can set patterns of gene expression. After receiving input from these sensors (sunlight is a good signal to set our clocks), the body uses molecular switches to adjust the timing of our internal clock with our surroundings. When the circadian clock becomes shifted, it can, in turn, change circadian rhythms and adapt body responses to environmental changes.
Circadian rhythm and disruption
A good example of circadian clock disruption is jet lag. When you take a long flight over multiple time zones your body’s sleep cycle becomes desynchronized from the environment. Gradually, your sleep patterns become regular again – learning from the cues of your surroundings.
What happens if we don’t return to normal, if the entrainment doesn’t have time to adapt due to constant disruptions, or if the clock and the rhythm are out of sync for different reasons? In general, this is considered a bad thing as it increases the risk for many chronic diseases.
Circadian rhythms are often disrupted in older individuals, and this disruption can affect many aspects of cellular function (metabolism, repair, stress resistance, inflammation, and proliferation), although it is not yet clear why this occurs. Many researchers believe that this disruption may increase risk for chronic disease in older individuals.
Is there anything we can do about this age-related disruption?
Potential regulators of the clock
Scientists at the Linus Pauling Institute have recently found that giving lipoic acid, a compound essential for cellular metabolism, to rodents helped to restore age-related changes in the circadian rhythms in the liver. The liver has a special circadian clock, one that can be entrained by lipoic acid. This effect of lipoic acid on the liver could help explain many of its observed effects on metabolism.
Lipoic-acidLipoic acid supplementation has previously been shown to enhance physical activity and memory in old animals and older adults, but it is unclear if these changes are all attributable to changes in the circadian clock. It is also unknown whether lipoic acid can affect circadian rhythms in other organs besides the liver.
Further research is needed to determine if lipoic acid supplementation can effectively modulate circadian rhythms in humans and what the optimal supplemental intakes might be to improve overall health.
For more information on the effects of lipoic acid on circadian rhythms, also see this study from the Linus Pauling Institute:
And for more information on lipoic acid, see the Micronutrient Information Center.
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