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Seasonal Shifts and Sleep Quality


It's mid-August and it’s time to start thinking about getting healthy for the fall. For some, the new year starts in January, for many the new year starts when school is back in session. As the days begin to shorten and nights lengthen, it's the perfect time to reset your day/night clock for your best health.

As with all mammals, humans are subject to the effects of the earth’s rotation and the solar day. As a result, most body processes change during the day. Certain signals influence your daily rhythms. The most potent signals are light and dark. This time of year, it’s easier to get up in the morning due to increased light, and more difficult to settle down for bed due to a later sunset. In the fall and winter, it is the opposite: easier to fall asleep at night due to the darkness, but harder to wake up in the morning. One of the best ways to increase health is through maximizing sleep, which leads to healthy levels of melatonin at night and optimal cortisol levels during the day. Cortisol follows the curve of light: it’s highest in the morning 30 minutes after waking and lowest in the evening and at night in darkness. Melatonin follows the curve of darkness: it increases at dusk and reaches its peak in the middle of the night, during sleep, when cortisol levels are lowest. The light of morning shuts down melatonin as it decreases from peak levels in the darkness of sleep, enabling cortisol levels to rise upon waking. Cortisol suppresses melatonin levels during the day and melatonin suppresses cortisol levels in the evening and at night. The day/night rhythm of cortisol, being at its highest in the morning and flattening out as the day progresses, is known as a “slope.” Flatter day/night cortisol slopes are associated with poor mental and physical health. Flatter slopes are also associated with a higher incidence of inflammation. Melatonin functions as a potent antioxidant protecting you against toxins as well as an anti-inflammatory. It’s hard to get away from light in our world. Any bright light at night or even dim light during darkness is disruptive to your day/night rhythms. It messes up your hormones. We know shift workers and/or night workers have a higher incidence of several diseases including cancer, diabetes, cardiovascular risks, obesity, mood disorders, age-related macular degeneration, metabolic and hormone disruption. It’s because of the imbalance of cortisol and melatonin. Light has such a powerful impact on human physiology that the International Agency for Research on Cancer (IARC) has classified shift work as a “probable carcinogen to humans.” The good news is that exposure to natural, full-spectrum light throughout the day can counterbalance the melatonin-lowering impact of electronic light at night. Daytime natural bright light exposure can cancel the negatives of light exposure at night. Refraining from screens one hour before bed time can help increase melatonin production, and light blocking glasses are available if evening exposure to indoor light and screens is not avoidable. Short bursts of outdoor light every couple of hours, or use of full spectrum light indoors, can mimic the bright light of the solar day, and decrease the melatonin-lowering effects of artificial light at night. In summary, get out in bright light during the day as much as possible and keep dim light in your house at night for greater health and well-being. Written by Krista Anderson Ross, ND and drastically modified for simplicity by Dr. Linda.

FUN FACT: Your ears never stop growing.

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