The Importance of Living in Accordance with the Circadian Rhythm
Sep 03, 2024I learned a great deal while researching this topic (started with sleep and quickly evolved to the circadian rhythm as a whole) and I have some clarity for why my own healthy habits have seemed to come so easily. I have unknowingly followed the circadian rhythm with every aspect of my day. I am a very type A personality, have always been an early riser, and like my routines. Apparently, this is the best way to live to maintain a well aligned circadian rhythm.
Sleep is an essential component to recovery, but the circadian rhythm is so much more than just sleep and sleep timing. The circadian rhythm has peak hours of energy and peak hours of recovery, which are regulated by release or suppression of hormones. It is best to time meals, exercise and sleep to align with the circadian rhythm for improved metabolism.
The circadian rhythm has direct impacts on metabolism and is related to the epidemics of obesity and diabetes. Why is this? The circadian rhythm regulates hormones associated with the desire to eat, the feeling of fullness-or satiety, feeling energized, and feeling tired. Consistently eating and sleeping at unusual circadian times may create a health risk to an individual due to metabolic disturbance and is more prevalent in individuals with a late chronotype. A chronotype is the preference for being an “early bird” or “night owl” and genetics may play a role in our individual chronotypes.
Exercise:
Research has shown that exercise first thing in the morning sets you up for a more energized day and improves your mood. In addition to these great benefits, sleep will come easier at night and the body will recover easier when exercise timing is in the morning- in generally healthy individuals. Why is this? Morning and evening exercise differentially affect night time body temperature and heart rate during sleep.
Morning exercise improves the quality of night time sleep by increasing the parasympathetic nerve activity (ability to relax), whereas exercising at night leaves the sympathetic nervous system activated (ability to act/react). Both body temperature and heart rate are increased in individuals who exercise right before bed.
Exercise in the morning for best sleep results: “sleep, eat, train, retreat”... in that order. Again, this is considering healthy individuals. Research shows that athletes, those with metabolic diseases, and evening chronotypes (night owls) may differ timing of eating and exercise. See specific excerpts from research at the end of the article.
Research has also shown a strong effect of regular exercise in the stability of the circadian rhythm and amplitude. Exercise may serve as a therapeutic tool to restore poor circadian rhythms. This finding is an important tool to use when adjusting your “body clock” after working a bout of graveyard shifts since exercise can aid in restoring your regular day-night cycle.
Hormones, Meal Patterns, Energy and Circadian Misalignment:
Cortisol is the lowest during the early biological night and the peaks in the biological morning. This is to allow for relaxation prior to sleep and for preparation of physical activity in the morning, again why exercise should be scheduled in the morning for best results of energy and reinforcement of maintaining the circadian rhythm.
I, personally start to feel relaxed around 5 in the evening and on the few occasions I have tried to do an afternoon workout, I felt sluggish because it was not part of my normal rhythm. I am also an early chronotype or “early bird” and the research shows that evening exercise throws off my circadian rhythm. In the cases of the “night owl”, early exercise can realign the circadian rhythm, but late exercise will not be as detrimental to these individuals as it is to “early birds”.
The body thrives on routine and lets you know when it does not like what you are doing. When cortisol remains high during sleep, or when sleeping at irregular hours, the sleep is not nearly as restful. With this sleep loss, cortisol may remain at high night-time concentrations, which is associated with a suppressed immunity and increased inflammation.
Glucose and insulin levels peak during the late biological night, lowering your blood glucose levels in healthy individuals. A disturbed circadian rhythm was associated with a significantly increased insulin response and to increased sympathetic nervous system activity. Changes in glucose and insulin responses can lead to decreased satiety as the remainder of hormones are thrown off as well. Refer to what the research says for the diabetic population regarding eating and exercise at the end of this article.
Leptin, is a hormone that suppresses the appetite-gives a feeling of fullness or satiety. Leptin night-time plasma levels are high when appetite decreases, favoring fasting and nocturnal rest, and low during the day, when hunger increases. This may play a key role in the ability to “fast” for longer periods. I have unintentionally been intermittently fasting for years because I stop eating in the early afternoon and don’t eat again until prior to my workout in the morning. This makes sense and I assume my Leptin regulation is properly aligned.
Ghrelin, which is produced in the stomach, pancreas and hypothalamus, is involved in stimulating the appetite and oscillates with feeding. “Elevated levels of ghrelin were found during the early part of the night in sleeping subjects, decreasing in the morning before awakening.” Sleep deprivation can increase ghrelin levels and the sensation of hunger, which is why lack of sleep is linked to weight gain.
Melatonin aids in sleep promotion and is released by the Pineal glad (mostly). Melatonin release is suppressed in the day light hours and is released in the dark hours. Artificial lighting disturbs melatonin release.
Macronutrient Timing:
A carbohydrate-rich diet is favored in the morning and higher-fat diet is preferred for evening meals. Why is this? Carbohydrates are metabolized better during the morning meal in relation to the glucostatic theory: the body metabolically responds more readily to a glucose stimulus, since the fasting glucose level is relatively stable at that time, and clearly indicates the first transient glucose decline. This goes back to the glucose and insulin peaks mentioned earlier regarding glucose and insulin timing.
Meals need to be aligned with the circadian rhythm. Timing of meals, with respect to food selection, meal frequency, meal intervals and meal size should be a structured routine. This structure results in positive metabolic effects and reinforces the strength of the circadian rhythm, though not as significantly as exercise. For most healthy individuals eating a carbohydrate and protein meal prior to exercising is ideal: remember the mantra- “sleep, eat, train, retreat”... in that order.
“Regular meal frequency creates more appropriate insulin sensitivity and lipid profiles compared with irregular meal frequency in healthy lean women, and irregular meal frequency led to a lower postprandial energy expenditure compared with the regular meal frequency, while the mean energy intake was not significantly different between the two. The reduced diet-induced thermogenesis with the irregular meal frequency may lead to weight gain in the long term.”
You cannot function through daily tasks without adequate sleep, let alone be on an exercise regimen attempting to lose weight or manage your weight. “Circadian alignment is crucial for body-weight management, and for metabolic health. In this context, circadian alignment consists of alignment of sleep, meal patterns and physical activity.” Get into a good habit of waking up early and going to bed with the ability to get approximately 7-8 hours of sleep. Eating a regularly scheduled and balanced diet and exercise in the morning.
What the research says:
Type 2 Diabetes and Type 1 Diabetes
“Exercise should be performed before feeding time, as it results in a significantly higher improvement in blood glucose control and lipid metabolism in contrast to post-meal exercise. However, for other diseases or exercise types, the individual condition of the person must be taken into account. A differentiated metabolic response to morning (fasting) and afternoon resistance exercise was observed in type 1 diabetics, in whom a greater incidence of hyperglycemia events occurred after morning than after afternoon exercise. Summarizing these results, an early feeding time with exercise before feeding seems to result in the greatest improvements in metabolic processes and is preferable for the treatment of diseases, but must always be adjusted to the individual.”
Recreation Sports vs Athletes
“Even though thermoregulatory processes are more efficient in the afternoon and therefore maximal performance is usually maintained at this time, for recreational sports with mostly short durations or moderate intensities no or hardly any negative effect in performance should be noticed by switching exercise time from evening to morning hours."
“For athletes, a proper exercise timing as well as an adequate carbohydrate supply during either high-intensity, long duration, or both, exercises seemed to be essential as it could be a limiting factor in maintaining exercise performance. Furthermore, replenishing used glycogen immediately after training sessions for better regeneration is important.”
Early vs Late Chronotypes
“People with a late chronotype (“night owls”) often experience social jetlag because they have early-morning work schedules that do not match their natural internal rhythms. People with a late chronotype are less physically active, have a higher BMI, and are at increased risk of developing type 2 diabetes and metabolic syndrome.Misalignment of circadian rhythms may be a contributing factor leading to obesity and metabolic dysfunction in late chronotypes. Relying on caffeine is not the answer and though in some cases it is necessary, it should only be a temporary solution. You have to make time to sleep, eat and exercise as it is essential to maintaining your health. As you have seen a major hormonal misalignment takes place when these factors not timed well or are not sufficient. Exercise has been shown as a strong factor in realignment of the circadian rhythm and should be considered as a primary therapy to improve sleep.”
“Although morning exercise was the ideal time to induce phase advances in the group as a whole, we also found that baseline DLMO influenced the phase advance caused by timed exercise. For later chronotypes, both morning and evening exercise advanced the internal circadian rhythm. In contrast, earlier chronotypes had phase advances when they exercised in the morning, but they had phase delays when they exercised in the evening. These results suggest the need for personalized exercise timing prescriptions based on chronotype. Late chronotypes, who experience the most severe circadian misalignment, may benefit from exercise in the morning or evening. On the other hand, evening exercise may exacerbate circadian misalignment in early chronotypes.”
If you need help with getting into a healthy routine, contact me through the Complete Balance PT website and schedule an evaluation.
This information is not intended to be used to treat or diagnose any medical conditions. Always consult your physician before making any changes regarding medications, eating patterns or starting an exercise program.
I look forward to hearing from you and keep an eye out for the next post!
-Karolina
Originally posted November 13th, 2022
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