Back when our ancestors were hunting and gathering, the turn of the seasons was a mysterious and life-changing event. Nowadays, seasonal shifts usually just prompt us to put on or take off a layer of clothing and switch our coffee order from hot to iced.
Even though we now have modern conveniences and technology that were inconceivable to our caveman forebears, our brains still function essentially the same way. That means that while you may not notice it, the change in seasons can dramatically affect your body, not least of all your ability to get a good night’s sleep.
A season for everything
First, a little planetary science. We experience seasons because of the Earth’s tilt—23.4 degrees, to be exact. As we make our annual 365.25-day journey around the sun, this tilt, or obliquity, causes different parts of the globe to receive different amounts of sunlight. Those variations in light and heat are why we have summer, winter, spring, and fall—and why the northern and southern hemisphere’s seasons are opposite.
The role of light in sleep
Just as Daylight Savings Time can disrupt our sleep in the short term, seasonal light fluctuations have a profound effect on our bodies in the long term. For starters, light is the chief influencer of the body’s production of melatonin, a hormone that plays a major role in regulating sleep/wake cycles. As days get shorter or longer, melatonin levels can rise and fall. Those shifts may make it harder to fall asleep and wake up easily. In fact, light’s melatonin-suppressing ability is why most electronic devices these days have a special screen filter for nighttime reading. (Here’s how to treat spring sleepiness.)
Too hot, too cold, just right
Like light, temperature also affects melatonin and is another leading factor in sleep quality. If the air is too cold, for example, melatonin production can suffer. But cranking up the thermostat isn’t the answer either. A room that’s overheated, in addition to being uncomfortable, can lead to dry nasal passages and leave you more vulnerable to colds and flu. Experts recommend keeping bedroom temperature pegged at 60–67 degrees Fahrenheit overnight. Learn how to sleep cool during the summer.
Allergies and sleep
In addition to changes in light and temp, new seasons bring a third challenge: allergens that cause sleep-disrupting congestion, itchy eyes, runny nose, and general misery. And it’s not just the tree pollen and ragweed that blow in through open windows when the weather is warm; it’s also the pet dander, mold, and dust mites that get trapped indoors when the house is closed up tight in the winter.
The change of seasons and sleep: your game plan
You can’t fight Mother Nature, as the saying goes, but you can try to fool her just a little bit. The best way to cope with seasonal transitions is to exert control over your sleeping environment. When it comes to light, temperature, and air quality, strive for year-round consistency and take advantage of technological benefits our ancestors never had, like blackout curtains, fans and space heaters, humidifiers, air purifiers and, of course, allergy meds.