Here we are in the thick of holiday season and I’m sure many of you are feeling the stresses and strains of this time of year. Having just done my ninth international/long haul flight of the year, I know I’m feeling it! This also got me thinking about harnessing the power of your chronobiology [or circadian rhythms], which is a topic I’m seeing gaining more and more mainstream media attention. As is often the case, the research findings presented are typically heavily biased towards men and male data, so I want to use my platform to ensure the female data is given valuable airtime. I want to also underscore the importance of women hitting the “big four” at this time of year [well, always, actually…].
"I consider the big four to be sleep, exercise, nutrition, and mindfulness. Take care of these four things in your life and you are doing a great job of taking care of yourself [and, by extension, those you love and who love you]."
So let’s dive in—here’s my take on how to take care of your chronobiology [or your circadian health] and the big four are …
Circadian Rhythms
The circadian rhythm is often thought to be ~24 hours and directly influences our daily body functions, such as temperature, hormone release, digestion, sleep, and mood. These rhythms cause physical, mental, and behavioral changes on a daily cycle and they mostly respond to light and darkness in your environment.
But, there are sex differences in our circadian rhythms. First of all, women have a shorter circadian period than men, around 23.5 hours versus 24.5 hours for men. Women have a different timing of their sleep-wake cycle where we see melatonin, a hormone that helps with the timing of circadian rhythms and sleep, secreted earlier in women than men. Core body temperature, which is at its highest before sleep and at its lowest a few hours before waking, follows a similar pattern, reaching its peak earlier in women than in men.
With circadian misalignment—which is common at this time of year due to travel-induced jet lag or stress-induced sleep deprivation—there is a change in how the body manages appetite and hormone release. In women, a decrease in the satiety hormone leptin and an increase in the hunger hormone ghrelin causes women to feel less full with their standard food intake. Men, on the other hand, have a marked increase in craving energy-dense foods, despite an increase in leptin and no changes in ghrelin.
So what does this show? Circadian misalignment alters energy balance factors in women and men through different pathways. While women show more changes in appetite hormones and resting metabolism, men experience more cravings without inherent changes in hormones or resting metabolism. Both pathways do lead to increased calorie intake under circadian misalignment, but understanding these sex differences means we can suggest specific ways to alter behaviors to reduce unfavorable body composition changes (especially in shift workers!).
High-Intensity Exercise Is The Answer
As you probably know by now, I am a huge advocate of high-intensity exercise, especially short, sharp, high-intensity training like sprint intervals of 30 seconds or less. For women, it’s like powerful medicine!
Sprint interval training (SIT) fires up your fast-twitch muscle fibers, which are those quick-burst, high-energy fibers that generally sit on the sidelines during endurance exercise. (They’re also the first to go with disuse and age.) SIT training strengthens and increases the amount of your energy-producing mitochondria, improves insulin sensitivity, and trains your body to burn more fat for energy when you’re not exercising. Research shows SIT also helps increase lean muscle mass, as well as improve power and cardiovascular fitness.
So if you’re feeling the stress of the holiday season, the first—and best—recommendation I can make is cranking up the intensity on one or two of your workouts.
The British Journal of Sports Medicine recently published a review of high-intensity exercise and mental health and found that short bouts of intense exercise was a winner for improving mental well-being and reducing anxiety and depression—something we all could use, especially at this time of year!
Eat to Nourish Body & Soul
Gah, the holiday season seems to be the time of year when women are bombarded with messages about how many minutes of exercise we need to do to burn the calories we’re about to consume in that cookie/glass of wine/any other holiday treat. I recognize that things are improving here and if you've been following me for a while, you’ll know I am not a fan of calorie counting. For example, 100 calories from protein reacts completely differently in the body than 100 calories of carbohydrate—and even then, 100 calories of carbohydrate from a piece of fruit reacts completely differently in the body than 100 calories of carbohydrate from an ultra-processed food.
When we are confronted by the holidays and #allthethings I think one thing that’s good to remember is that if you are generally mindful of the quality of the food you are eating and you make an effort to move daily (this does not have to be structured exercise!) then you are already in a great place. I want you to remember that life is full of adventures, and the holidays—although, yes, stressful at times—is a time for enjoying life, whether that’s with friends and family or taking off on your own for peace of mind. Wherever you land over this period, keep body positivity in the forefront. Eat to nourish your body and soul—and yes, oftentimes, that does include eating the damned cookie!
Mindfulness Can Help You
Sometimes you just need to escape the holiday madness and one of the best ways to do that is carving out time to incorporate meditation or mindfulness into your every day. I know, I get it—I know this isn’t always possible or easy, but I’ve honestly found (and the research backs this up) that it’s something that helps ground and center me, particularly at times when life feels hectic and uneasy. For me, the true gem of mindfulness is about finding parasympathetic responses in short bursts, that is, encouraging your nervous system to slow down, pause, rest, and relax, even if just for a few minutes. Non-Sleep Deep Rest (NSDR) meditation [search your podcast platform for NSDR for great short mediation-leading podcasts] is something that can definitely help here, as is my Microlearning course on Adaptogens. Taking time each day to do this is something that I know has helped scores of women, particularly at stressful times like the holiday season.
