Although we do not hibernate the same way as bears and chipmunks, we humans do respond physically to the winter season. Both colder temperatures and decreased natural light trigger responses in us we may or may not be aware of. Modern life often requires us to act against these natural changes, leaving us more vulnerable to disease and unhealthy tendencies.
Winter is the traditional season for slowing down. In temperate regions humans have always had to find ways to stay warm and fed during the cold dark days of winter. We stayed indoors around the hearth, slept much more, and limited our activity. These days we act as though winter is summer, and we work, play, and sleep as though the seasons are all the same.
But winter is still winter. Even in milder climates like California and Florida our bodies work harder to stay warm, triggering increased appetites and body-fat build-up for energy storage. Instead of slowing down we maintain our schedules and increase our stress levels with holiday planning and expectations. Add that winter is also the peak season for colds, influenza, and bronchitis, and it is easy to understand why we often feel less healthy this time of year.
Shorter days with weaker sunlight affect our circadian rhythms (sleep-wake cycle). We begin to produce melatonin, the hormone that naturally induces sleep, at twilight regardless of the season. In the winter, twilight arrives at mid- to late afternoon. Our internal biological clock is telling us to go to sleep until dawn, which doesn’t arrive until mid-morning despite daylight savings time. So by getting up early for work and going to bed long after sunset we are forcing ourselves to act against our natural responses. Studies show this can weaken your immune system right when viruses begin appearing.
Less sunlight also decreases the body’s Vitamin D production. Our skin produces Vitamin D for us in sunlight, but the combination of warm clothes, weaker light, and more indoor time means our vitamin D production drops dramatically in winter. The effects of this decrease are wide-ranging, including seasonal affective disorder (SAD) and a weakened immune system. Less widely known is the increased risk of acute depression, hyperglycemia, osteoporosis, insulin resistance, hypertension, and heart disease.
Given that we are not going to quit our jobs and sleep 12 hours a night, what are healthy responses to the season? Do get enough sleep to best cope with the physical and emotional stresses of the season. Watch what you eat and favor fruit, vegetables, and whole grains over too many holiday sweets and overindulgence. Get outside in the daylight more, even if just walking to the store. Consider supplementing your Vitamin D intake (more on this in the next issue, sign up for email delivery here). And give yourself permission to take it easy occasionally—let a little hibernation into your life!
- Rebecca Taggart