This article originally appeared in Well+Good.

Thanks to summer’s hefty serving of daylight, you're bound to experience boosted levels of the feel-good hormone serotonin during the season, not to mention you'll have more hours in each day for outdoor activities and restorative time in nature. But while the abundance of sunlight can be super beneficial for those aforementioned reasons and others, it may also be part of the reason why you sleep less in summer months.

Light plays a big role in regulating our circadian rhythm (the 24-hour sleep-wake cycle). The natural rise in your body’s creation of melatonin helps you drift off at night, while a dip in melatonin (and subsequent spike in alertness-promoting cortisol) in the morning is what rouses you awake. On both ends, light influences when and to what degree those hormones are produced—and since there's more light in the summer in general, our sleep can pay the price.

“Summer’s longer days can contribute to delayed melatonin production, ultimately leading to sleep issues,” says clinical psychological Michael J. Breus, PhD, chief sleep advisor at Purple.