In northern climates, February has a particular heaviness. Even though we’ve passed the longest night of year, the days often feel darker, longer and more draining than December ever did. For society’s “night owls,” whose internal clocks naturally run later, this stretch of winter can be especially challenging.
As a biological anthropologist who studies sleep (and a night owl living in the North), I see this unfold every winter, and science offers a clear explanation for it.
The major reason can be found in our circadian system, the body’s internal 24-hour clock, which relies on morning light to stay aligned with the Earth’s day. After months of dim, delayed sunrises, that system is running low on the cues it needs to keep us alert and energized.
