You’ve probably heard a lot about circadian rhythms
in terms of sleep/wake patterns and eating patterns. But, did you know
that your circadian rhythms do much more than that? Our entire body is controlled
by diurnal oscillations, which is why some activities seem easier at
certain times of the day. This influence has the potential to impact
the best times to take medication, eat your meals, and take your nutritional
supplements.
Many complementary medicine traditions, such as
Ayurveda and Traditional Chinese Medicine, incorporate
circadian rhythms in their treatments. Western medicine is starting to
recognize the power of these rhythms to both facilitate treatments and contribute
to dysfunction when they are in disarray. Let’s learn more about the influence
of these powerful rhythms.
The Power and Importance of the Circadian Rhythm
Every process in your body, including reacting to
oxidative stress, the composition of your microbiome, and the levels of your
intracellular proteins, all have some type of oscillating
pattern that fits within a daily 24-hour rhythm. Your
body upregulates certain components of metabolism and mechanisms
required for self-defense during the hours it expects to need them and
down-regulates them during periods of rest.
There are several circadian transcription factors
that control positive and negative feedback loops in the cells to determine
functions of key organs and systems, including your heart, lungs, immune
system, and metabolism, as well as the intracellular processes, such
as cellular respiration and DNA repair. In fact, this internal clock
system regulates roughly one-third of your body’s entire gene
activity! Your genetic code regulating these systems affects your body’s
timing for peak performance, such as whether you are a morning person or
a night owl.
The central regulator of your circadian rhythms is
the suprachiasmatic nucleus, SCN, which is found in the hypothalamus in
your brain. It does this largely through controlling the secretion of
melatonin, which is the main circadian hormone.
Health
problems associated with circadian rhythm
disruption include:
– Allergies
– Asthma
– Cardiovascular disease
– Hypertension
– Insomnia
– Jet lag
– Metabolic disorders
– Neurological disorders
– Psychiatric disorders
– Social jet lag
– Stroke
– Asthma
– Cardiovascular disease
– Hypertension
– Insomnia
– Jet lag
– Metabolic disorders
– Neurological disorders
– Psychiatric disorders
– Social jet lag
– Stroke
Disruptions in the circadian rhythm also reduce your
life expectancy. Furthermore, as you age, you become more sensitive to
disruptions in the circadian rhythms—and less sensitive to synchronization
techniques.
Metabolism, Dietary Enzymes, and Feeding Times
Circadian rhythms regulate your digestion
and metabolism. In the proper rhythm, gastric
emptying, thermogenesis, and motility rates reach their
peak in the morning. During the active phase of the day, bile acids and
nutrient transporters are regulated and more active, as is energy
metabolism. Conversely, detoxification becomes more
active during the rest phase.
Several factors involved in regulating
metabolism have a close relationship with the core clock:
– AMPK: a signal of low cellular energy
and one of the most important sensors of nutrient status
– PGC-1a: regulates energy metabolism
– PPARa: regulates genes involved in glucose and lipid metabolism
– REV-ERBa: involved in the differentiation of adipocytes
– RORa: regulates lipid storage in skeletal muscle and lipogenesis
– SIRT1: a histone deacetylase that helps to signal transcription and stability of genes if dependent upon NAD+
– PGC-1a: regulates energy metabolism
– PPARa: regulates genes involved in glucose and lipid metabolism
– REV-ERBa: involved in the differentiation of adipocytes
– RORa: regulates lipid storage in skeletal muscle and lipogenesis
– SIRT1: a histone deacetylase that helps to signal transcription and stability of genes if dependent upon NAD+
For example, CLOCK-BMAL1 and
omega-3 fatty acids activate some nuclear
receptors involved in energy homeostasis, including
PPARs. Glycogen synthase functions during the active period
and glycogen phosphorylase during the resting
period. Polymorphisms and other variants in certain genes related to
circadian rhythms are associated with obesity and metabolic
disease, some of which are affected by certain diets, such as higher
carbohydrate intake or higher fat intake.
Blood glucose and lipid
regulation are dependent upon diurnal
rhythms as well. Consuming a high-fat meal raises triglycerides in the
blood more at night than the same meal consumed during the day. Important
adipokines, including leptin and adiponectin, also have diurnal rhythms.
To break it down, during the
day when you are awake, you have:
– Adiponectin production
– Decreased synthesis of cholesterol
– Glycolytic metabolism
– Increased synthesis of bile acids and glycogen
– Increased uptake of fatty acids
– Lipogenesis
– Secretion of insulin
– Decreased synthesis of cholesterol
– Glycolytic metabolism
– Increased synthesis of bile acids and glycogen
– Increased uptake of fatty acids
– Lipogenesis
– Secretion of insulin
During night when you are fasting and sleeping, you
have:
– Biogenesis of mitochondria
– Catabolism of lipid
– Gluconeogenesis and glycogenolysis
– Leptin and glucagon secretion
– Oxidative metabolism
– Catabolism of lipid
– Gluconeogenesis and glycogenolysis
– Leptin and glucagon secretion
– Oxidative metabolism
It is not just the human cells in your body that have
a daily rhythm; your microbiota impacts—and is impacted
by—circadian rhythms as well. Melatonin exists in
the gut in levels that are about 400 times the level in the pineal
gland in the brain where it acts as a modulator of bowel
function. One study found that melatonin might impact the microbiota in
the gut as well as regulate other components of the circadian rhythm, like
sleep.
