Sleep schedules and human productivity depend less on habits and more on biological characteristics, according to Popular Science.

Scientists note that dividing people into “early birds” and “night owls” is an oversimplification. In reality, the concept of chronotypes—individual biological rhythms that determine periods of activity and rest—is more accurate. These rhythms are shaped by genetics, age, and environmental factors.

Experts explain that sleep preferences change throughout life: children tend to wake up early, adolescents shift toward later schedules, and with age, people often return to earlier rising. However, a person’s underlying predisposition to a specific chronotype generally remains stable.

External factors also play a significant role. Exposure to light, especially artificial light, can shift the body’s internal clock by suppressing the production of melatonin. For example, frequent use of electronic devices in the evening can delay the onset of sleep.

Research also shows that genetics influences chronotype: scientists have identified hundreds of factors linked to preferences for morning or evening activity. It is believed that this diversity in sleep patterns may have had evolutionary benefits, allowing ancient communities to remain alert at different times of day.

Some experts propose a more detailed classification of chronotypes, including categories such as “bears,” “wolves,” “lions,” and “dolphins,” reflecting different activity patterns and sleep sensitivity.

At the same time, scientists emphasize that there is no universally “best” sleep schedule. Early rising is often associated with more stable mental and physical health, while “night owls” may demonstrate high cognitive flexibility and strong memory. However, chronic sleep deprivation—regardless of chronotype—increases the risk of obesity, depression, cardiovascular disease, and type 2 diabetes.

Experts highlight that the key factor is aligning one’s lifestyle with internal biological rhythms. Maintaining a consistent sleep schedule, ensuring sufficient rest, and planning activities during peak productivity periods can help reduce stress and prevent burnout.