Another bodily process that is heavily intertwined with sleep is our circadian rhythm.
This rhythm is part of our chronobiology—our body’s natural cycles (mental, physical, and emotional) that are affected by solar and lunar rhythms, also known as biological rhythms. Interestingly, this process occurs in all living organisms.
In your brain there’s a small but very important region called the hypothalamus. Among its other functions (regulating body temperature, controlling appetite, managing sexual desire, and regulating emotional responses), the hypothalamus is responsible for the release of hormones and the maintenance of daily physiological cycles. More specifically, the suprachiasmatic nucleus (SCN) region of the hypothalamus is our internal clock. Keeping this region healthy (through exercise, adequate sleep, and a healthy diet) is crucial to your overall health and wellness.
It would be amazing if we had the financial and responsibility-related freedom to schedule our life around our circadian rhythm, but unfortunately this isn’t a reality for 99 percent of the population; that said, there are likely some ways you can adjust your lifestyle to parallel your body’s natural rhythms more closely and therefore act more harmoniously with them.
Even though you might not have the time to schedule your day to mimic the exact desires of your circadian rhythm, this doesn’t mean you need to actively fight it, day after day. Most people battle with their natural rhythms, and over time the result is more and more internal fatigue—which results in the body and mind not getting what they need, when they need it.
Here’s an example provided by chronobiology.com of a typical circadian rhythm for someone who wakes up early in the morning, eats lunch around noon, and goes to bed around 11 p.m. As we’ve seen, there are many factors that affect the body’s timing, but this will give you a rough idea of timeline—it’s kind of like your body’s to-do list:
6 a.m. The body’s systems awaken
7–9 a.m. Hormones are at their peak
8–9 a.m. Highest pain threshold
10 a.m.–12 p.m. Fully fit and wide awake—brain is at its most efficient
12 p.m. Time to eat—digestion in top gear
1–2 p.m. Afternoon low—time for a nap
3–4 p.m. New upswing—phase of learning and long-term memory
5–6 p.m. Second peak—best time for manual work (body temperature and grip strength peak)
6–9 p.m. Regeneration and relaxation, optimal sense of smell and taste
9 p.m. Stomach rests—time to stop eating
11 p.m. Time for bed
4:30 a.m. Lowest body temperature
As you probably know, not everyone has the same ideal sleep and wake schedule—but the variation in ideal sleep and wake times isn’t as great as you might think. According to Dr. Michael Breus, who’s often referred to as “America’s Sleep Doctor,” genetics plays a role in determining your internal clock. Your chronotype is largely determined by a gene called the Period Circadian Regulator 3 (PER3). It’s a circadian gene that determines your ideal sleep and wake schedule based on its length. If your PER3 gene is longer, you’re more likely to be an early riser; if it’s shorter, you’re more likely to prefer rising late.
Dr. Breus has developed an in-depth questionnaire that places people into one of four chronotypes (Dolphin, Lion, Bear, and Wolf). Here’s a brief depiction, as well as the ideal wake-up time, for each of the four chronotypes. To find out your chronotype, I recommend that you head to his website (thesleepdoctor.com) and take the quiz.
Lion. These people typically wake up early with lots of energy (you know the type . . . cue the slightly envious eye roll) and are exhausted by early evening; ideal wake-up is 5:30 a.m.; represents about 15–20 percent of the population.
Dolphin. These folks tend to be light sleepers and are more likely to be diagnosed with insomnia; ideal wake-up is 6:30 a.m.; represents about 10 percent of the population.
Bear. These individuals have a circadian rhythm that follows the rising and setting of the sun and usually require a full eight hours of sleep; ideal wake-up is 7 a.m.; represents about 50 percent of the population.
Wolf. These people have a hard time waking up early and are most energetic in the evenings; ideal wake-up is 7:00–7:30 a.m.; represents about 15–20 percent of the population.
Although Dr. Breus provides the ideal sleep time for each chronotype, I believe there’s more variation in this due to people’s wildly different lifestyles. Those who are busier and get regular physical activity will have undoubtedly accumulated more adenosine in their brains throughout the day—this will drive their desire to sleep (so that proper recovery can take place).
Also, the “ideal” times based on your chronotype can be shifted. While you’re unlikely to turn a Wolf into a Lion, through lifestyle choices (when you consume caffeine, meal timing, exercise schedule) you can move it a bit closer to your ideal (for instance, you really want to be a morning person) or your reality (you must get up early for work).
Consider this, you call yourself a “night person” (as many falsely people do), yet you feel tired most days even though you’re getting the “recommended” amount of sleep. Perhaps your ancestral biology would rather you woke up earlier, but you’ve fought it for years and therefore believe that you’re a Wolf. So, if you’ve been living with chronic exhaustion perhaps it’s time to make some adjustments and try something new. It will take a few weeks to adjust (both mentally and physically), but you may feel that you’re more energetic and happier with an earlier bedtime and wake-up schedule.
JOSEPH GIBBONS
Author, Speaker, Professor, Mental Health First Aid Instructor
Helping individuals & organizations overcome the life obstacles that impede their journey towards optimal physical, mental, and spiritual health.
1 Gabriele Andreatta and Kristin Tessmar-Raible, “The still dark side of the moon: Molecular mechanisms of lunar-
controlled rhythms and clocks,” Journal of Molecular Biology 432, no. 12 (2020): 3525–46.
doi:10.1016/j.jmb.2020.03.009
2 David K. Welsh, Joseph S. Takahashi, and Steve A. Kay, “Suprachiasmatic nucleus: Cell autonomy and network
properties,” Annual Review of Physiology 72, no. 1 (2010): 551–77. doi:10.1146/annurev-physiol-021909-
135919
3 “Home,” Chronobiology.com, September 17, 2021. https://www.chronobiology.com/
4 Danielle Pacheco, Chronotypes: Definition, types, and effect on sleep, Sleep Foundation, September 19, 2022.
https://www.sleepfoundation.org/how-sleep-works/chronotypes
5 Simon N. Archer, Donna L. Robilliard, Debra J. Skene, Marcel Smits, Adrian Williams, Josephine Arendt, and
Malcolm von Schantz, “A length polymorphism in the circadian clock gene PER3 is linked to delayed sleep
phase syndrome and extreme diurnal preference,” Sleep 26, no. 4 (2003): 413–15.
doi:10.1093/sleep/26.4.413
6 Michael Breus, Chronotype quiz, The Sleep Doctor, December 13, 2022. https://thesleepdoctor.com/sleep-
quizzes/chronotype-quiz/
Comments