"In the depths of winter, I finally learned that within me lay an invincible summer." Albert Camus 

For people in the northern hemisphere, winter fatigue typically takes hold in early December, lasting until the spring. The dark and cold times can feel tiring and demotivating, making hibernating under blankets with hot tea feel more inviting than nearly anything else. 

In our productivity-focused society, you might interpret your winter fatigue as a sign that you've lost interest in your career, and your zest for life, and look frantically for a boost of energy or motivation. From this perspective, it can feel tempting to power through your sluggishness with caffeine or another quick fix.

Yet many people overlook the fact that the season change stresses the body. Winter tiredness, sluggishness, and low motivation are natural and even functional responses to the reduction in sunlight the winter months bring with them. To respond optimally, it's helpful to use strategies that naturally support our energy levels, while at the same time honoring the winter season as a time for regeneration, reflection, and slowing down. 

The sun's blunt departure: The science behind winter fatigue 

In the northern hemisphere, the earth's axis tilts away from the sun beginning in December and remains this way until the early spring. With sunlight exposure being the most significant driver of our circadian rhythms, winter fatigue usually reflects the loss of sun exposure the cold, dark months bring with them. 

Sunlight exposure halts the release of the sleep-inducing hormone, melatonin. Since sunlight delivers messages that tell our bodies that it's time to be active and alert, the less sunlight exposure you have, the more melatonin you produce, making you susceptible to becoming tired earlier in the day. 

Sunlight exposure also allows our bodies to synthesize a critical fat-soluble vitamin. Vitamin D plays vital roles in everything from calcium absorption, to immune function, to bone and teeth health [1]. And more specifically, studies have pointed to links between vitamin D deficiency and fatigue [2]. 

Winter fatigue and its implications–A problem or an adaptation? 

While the loss of sunlight impacts nearly everyone, the medical community also recognizes fatigue, weight gain, and low mood as symptoms of seasonal affective disorder (SAD). 

Yet feelings of tiredness, sluggishness, and low motivation during the winter months can also be products of the mismatches between our bodies and our modern ways of life. For hundreds of thousands of years, our ancestors built fat reserves to survive the scarce resources of the winter. Theoretically, winter fatigue might reflect the advantage our ancestors found in laying low during the winter months. Burning a ton of energy during the cold months could have increased our need for fuel, depleting our food supply faster (among other issues).

With that in mind, we might interpret our lower energy levels during the winter months as intelligent, functional adaptations to the changing signals in our environment. Yet because our plans and responsibilities don't simply disappear during the winter, we can make micro-optimizations that powerfully support our performance and energy levels while giving our bodies opportunities for rest and rejuvenation.

1. Replace your alarm clock with early morning sunlight

Going outside, without sunglasses, even for as little as 10 minutes, is vital: The early morning sunlight issues messages to our bodies we cannot get at other times of the day.

Early morning sunlight boosts our mood, energy, and focus levels, while simultaneously setting the template for regular sleep rhythms. Early morning light exposure will not only align your energy levels with the sunlight, but it will help you set in motion a consistent wake up and bedtime rhythm.

The early morning sunlight delivers a signal through the eye's ganglion cells that tell the brain the time of day, sending peptides that serve as wake-up signals for the body, promoting alertness and focus [3]. This interaction also sets in motion a timer that triggers the release of melatonin 12 to 14 hours later [4], promoting tiredness a few hours after the sun sets. The amount of time you’ll want to spend outside depends on the time of year and where you are, but as little as 10 to 25 minutes can be enough to see the benefits of this practice.

2. Limit high-sugar and carbohydrate meals

In the winter, carbohydrate-heavy foods give us a rapid energy and mood boost, which can feel alluring if our energy levels are already low. Afternoon energy drops can be a normal part of our circadian rhythm, but foods high in carbohydrates and processed sugar intensify the afternoon slump by causing blood sugar roller coasters. These typically take the form of a sharp and rapid upswing in our blood sugar that falls just as abruptly. 

During the winter in particular, it can be useful to focus on foods that provide slow-releasing fuel: natural fats, proteins, vegetables, nuts, and seeds. Unlike carb- and sugar-rich foods, natural fats provide long-lasting energy and mental clarity since many of the structural components of the body, such as the brain’s cell membranes, are made of fat.

3. Avoid caffeine for at least 90 minutes after waking up

If you drink caffeine as soon as you get out of bed, you might be trading an immediate jolt in alertness for a mid-morning or afternoon crash. 

There are two reasons this can happen. The first is that our circadian rhythm coordinates the release of cortisol, which peaks within 45 minutes after we wake in the morning [5]. If you drink caffeine during this window, you’re ingesting it at a time when your levels of alertness are already high. 

Also, caffeine works by blocking the actions of the sleep-promoting neurotransmitter, adenosine, which accumulates the longer we're awake [6]. When you drink coffee as soon as you wake up, you'll block adenosine in the short term, but without an opportunity to dissipate naturally, it will build up and lead to a focus and energy crash a few hours later.

Conversely, if you focus on getting sunlight and hydration in the morning, your adenosine levels will naturally subside within the first few hours of being awake, making the sudden energy crash less likely. If you currently have an early-morning caffeine habit, start by waiting 15 minutes before your first cup, gradually increasing until you're comfortable waiting 90 minutes or longer.

4. Spread movement throughout your day

Although exercise can feel like the last thing you want to do in the cold, it’s the ideal way to create momentum. Paradoxically, exerting yourself through exercise helps generate more energy. Physical exertion stimulates the production of more mitochondria within your muscle cells. The more mitochondria you have working for you, the more effective your body becomes at using your food for fuel, supporting your energy levels and stamina [7].

Although gyms and other public exercise facilities are excellent in many ways, they can intensify the already-common habit of compartmentalizing movement. Instead of seeing it as inherent to our lifestyle, exercise can become an isolated activity that takes place apart from leisure, work, and other activities.

Instead, spreading low-to-moderate intensity exercise throughout your entire day might better support your focus and energy levels when compared to shorter, yet contained periods of high-intensity exercise. A study from the University of Georgia reported that people struggling with fatigue found greater relief through low-to-moderate movement (i.e. slow, leisurely walking) than more rigorous exercise [8]. In the study, many participants reported that rigorous activity actually made them more tired.

While your current fitness level will influence how you respond to vigorous exercise, consider focusing on movement throughout the day (along with whatever exercise routine you're already following). For example, you might do lunges, jumping jacks, or alternate between sitting and standing to sharpen your energy levels throughout your work day.

5. Strategically stress your body 

Dr. Anna Lembki, the author of Dopamine Nation, pointed to an intriguing finding from recent neuroscience research–that pleasure is "co-located" with pain, meaning that the parts of the brain that process pain also process pleasure. When you feel an extreme of either end of the spectrum, the brain must also process the other to maintain balance [9].

This phenomenon partly accounts for why we can increase our resilience through strategic, controlled exposures to stress. Exercise, fasting, or exposure to extreme temperatures are examples of "hormetic stressors": acute stressors you can voluntarily practice to train your body's healthy, adaptive response.

For example, research into the impacts of full-body cold immersion have shown that the initial sympathetic response that comes from the initial shock of the cold water leads to the subsequent, slow release of mood-improving neuromodulators like dopamine and adrenaline [10]. Incorporating hormetic stressors into your day is a way of trading a brief exposure to stress for higher baseline levels of well-being that can last for hours afterward. 

6. Take intelligent naps 

Tiredness in the afternoon isn't only the product of diet or lack of sunlight exposure: According to sleep medicine expert Dr. Michael Breus, between 1 and 3 pm, our body temperatures naturally drop while melatonin levels rise, making us sleepy in the afternoon.

Optimizing your nap's timing and duration can ensure your naps refresh you, rather than interfere with your sleep or leave you groggy in the aftermath. The ideal nap time is approximately seven hours after you wake up for the day [11]. This is the window where you're most likely to strike the ideal balance between rapid eye movement (REM) and slow wave (deep) sleep, which will help you wake up feeling refreshed.

When it comes to timing, you'll want to either nap for 25 minutes (where you'll wake before entering deep sleep) or 90 minutes (where you'll move from light to deep to REM then back to light sleep) [11]. In all cases, the goal is to wake from a lighter stage of sleep so you avoid post-nap grogginess.

Discomfort can scare you or light a fire inside you

"The cave we fear to enter holds the treasure we seek." Joseph Campbell

In many ways, making the most out of the long, dark season comes down to choosing what kind of discomfort you're willing to face. Since loss of sunlight inevitably puts stress on the body, in many cases, we’re faced with two different kinds of discomfort: the pain of challenging ourselves to get up early, and get sunlight and movement, or the pain of later feeling sluggish because we stayed cozy yet stationary under blankets.

Though many of the above tips can feel demanding at first, their payoff will come in the form of steadier levels of focus and energy, even when it's grizzly and freezing outside.

Remember that you don't need to make all these changes at once. When you implement one at a time, any results you see will serve as a natural motivator to add further optimizations. 

Sources: 

"Vitamin D - Fact Sheet for Professionals." National Institutes of Health: Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/

1. Alavi, NM, Madani, M, Sadat, Z, et al. Fatigue and vitamin D status in Iranian Female Nurses. Global Journal of Health Science. 2015 17; 8(6): 196-202. doi: 10.5539/gjhs.v8n6p196

2. Dodson, ER, Zee, PC. Therapeutics for circadian rhythm sleep disorders. Sleep Medicine Clinics. 2010. 5(4):701-715. doi: 10.1016/j.jsmc.2010.08.001

3. Crispim, CA, Zimberg, IZ, et al. Relationship between food intake and sleep pattern in healthy individuals. Journal of Clinical Sleep Medicine. 2011. 7(6). doi: https://doi.org/10.5664/jcsm.1476

4. Dowd, JB, Ranjit, N, Do, DP, et al. Education and levels of salivary cortisol over the day in U.S. adults. Annals of Behavioral Medicine. 2011. 41(1). doi: 10.1007/s12160-010-9224-2

5. Fredholm, BB. Adenosine, adenosine receptors, and the actions of caffeine. Pharmacology & Toxicology. 1995. 76(2): 93-101. doi: https://doi.org/10.1111/j.1600-0773.1995.tb00111.x

6. Golen, T, Ricciotti, H. (2021, July 1). Does exercise really boost energy levels? Harvard Health Publishing. https://www.health.harvard.edu/exercise-and-fitness/does-exercise-really-boost-energy-levels

7. Peutz TW, Flowers SS, O'Connor PJ. A randomized controlled trial of the effect of aerobic exercise training on feelings of energy and fatigue in sedentary young adults with persistent fatigue. Psychotherapy and Psychosomatics. 2008. 77:167-174. https://doi.org/10.1159/000116610

8. Lembki, A. (2021) Dopamine nation: Finding balance in the age of indulgence. Dutton.

9. Sramek, P, Simeckova, M, et al. Human physiological responses to immersion into water of different temperatures. European Journal of Applied Physiology. 2000. 81(5): 436-42. doi: 10.1007/s004210050065

10. Breus, M. [Commune]. Dr. Michael Breus: To nap or not to nap? [Video]. YouTube. https://www.youtube.com/watch?v=q5zdjxYvt-0