“Humans are either morning larks or night owls, and can't change.”

It's a common observation that some individuals naturally spring out of bed at dawn, full of energy, while others thrive in the late hours, feeling most productive as the day winds down. This leads many to believe that our internal clocks are rigidly fixed from birth, assigning us permanently to one camp or the other. This widespread notion stems from our personal experiences and the consistent patterns we observe in friends (Review), family, and colleagues, making it seem like an unchangeable aspect of our identity.

Scientifically, there's a significant truth to this perception. Our predisposition to be an early bird or a night owl, known as a chronotype, is indeed heavily influenced by our genes. Research has identified specific genetic markers that dictate the timing of our circadian rhythm, the internal process that regulates the sleep-wake cycle over a 24-hour period. This genetic blueprint explains why some people genuinely feel more alert and perform better in the morning, while others are naturally inclined towards evening activities.

However, while genetics lay a strong foundation (Review) for our chronotype, they don't represent an entirely unyielding fate. The verdict of plausible acknowledges that a degree of adaptation and shift is possible. Our lifestyle choices, such as maintaining a consistent sleep schedule, regulating exposure to light (especially bright light in the morning for night owls or dimming lights in the evening for larks), and even diet and exercise, can influence our internal clock. While it might be challenging to completely override deeply ingrained genetic tendencies, these external factors can nudge our chronotype over time, offering some flexibility in our sleep-wake patterns.