A season of high notes, summer is the time many of us spend the rest of the year yearning for. Humans are heat lovers, sun worshipers, light chasers. And summer’s long, bright, warm days give us plenty to soak up, often finding us filling the extra daylight hours with leisure and play. Credited for enhancing mood, creativity, and cognitive functioning, when it comes to feeling energized, natural light’s your girl. Environmental psychologist Sally Augustin describes it as a “magic elixir that does great things for what goes on in our minds…[with] a powerful, nearly primordial effect on our well-being.”
But if you’re not careful, the extra light can also be the culprit keeping you from a good summer slumber. Paired with hot temps, busy social calendars, and maybe a smidge too many drinks, night light is keeping our summer sleep satisfaction score low. Something that feels especially unfair while we’re trying to live the good life.
Why? The body clock, or suprachiasmatic nucleus, is an extremely light-sensitive system. Helping it keep time is melatonin, the hormone that tells your body when it’s time to snooze. Receiving light patterns delivered from the eye to the brain, the circadian pacemaker doles out melatonin as day dims—a time that shifts later and later as the calendar marches toward midsummer and we spend more and more hours basking in the spotlight.
Melatonin’s secretion window is slim in summer, meaning we’re neither primed to fall asleep easily or to sleep as sound. Add to that early dawns and lingering evening twilight—and all the stimulation we stuff ourselves with in the middle—and it can be especially challenging to keep our summertime sleep needs in step with the skies.
“Light is the most important external factor affecting sleep,” writes Eric Suni for the Sleep Foundation. “While most people intuitively know that it’s easier to sleep when it’s dark, the link between light and sleep goes much deeper.”
Depending on how near you live to the Equator, the summer months offer as much as twelve hours of darkness and as little as zilch. Costa Ricans, for example, see the sun dip below the horizon by 6:30 p.m. almost every day, while inhabitants bordering the Arctic Circle—in places like Alaska, Iceland, Greenland, Scandinavia, and parts of Russia—live, breathe, and sleep with solar asynchrony. Their summers are short but the days are never ending, the sun high in the sky for 20–24 hour spans. They call it Midnight Sun.
To squelch the daylight’s nighttime persistence, people who live in these places make their sleep spaces as dark and cool as possible. And they wake rested. Adding to their abundant happiness and wellness accolades, Scandinavians are among the world’s best-slept people (They also utilize the two-duvet method—ever tried it? It just might keep you from getting a sleep divorce.)
Sunlight is easy to point fingers at when it comes to summertime insomnia, but it’s far from the only light source to blame for poor sleep. Ambient light leaking into your bedroom through doors or windows—at any time of year—will take a toll on sleep quality, and your longterm health.
“New research suggests that one night of sleep with just a moderate amount of light may have adverse effects on cardiovascular and metabolic health,” NPR reports on a study authored by Dr. Phyllis Zee, director of the Center for Circadian and Sleep Medicine at Northwestern University.
Zee’s study continues the research on how melatonin disruption is linked to cancer and diabetes, but also indicated that even a “small amount of light was enough to activate the sympathetic arm of the automatic nervous system—what’s responsible for the body’s fight or flight response.” More than the effects from decreased melatonin, Zee’s study showed that sleeping in low-level light was keeping the body alert and activated, in a state of stress. “It's almost like the brain and the heart knew that the lights were on, although the individual was sleeping," she says.
So, to keep your sleep from becoming too light, eliminate it. Invest in high-quality blackout curtains, remove light-emitting devices from your bedroom, and turn off hallway and household lights that might slip in through cracks and crevices. Then, when you’re awake, submerge yourself in light. Throw open the shades, go outside. Being in light—even artificial light—during the day will regulate and strengthen your circadian rhythm, helping it to establish an alert and productive wake time and a deep and restful sleep time.
A few hours before it’s time to wind down each day, even if the sky isn’t sunsetting, start lowering lights around the house, powering down devices, and cooling your space (below 67 degrees is ideal). And, if you can, do your wind-down routine at the same time every day so all of your many, many body systems know what to expect and how to respond accordingly.
Waking up to sunlight streaming through the windows is a great pleasure, but is it worth sacrificing your health and wellbeing? (Especially when you have a waking clock that’s been described as sounding like angels pulling espresso shots?) The poet Wendell Berry wrote: “To go in the dark with a light is to know the light. To know the dark, go dark.” There is beauty in darkness. And also good sleep.