chronotype

Chronotype is an individual’s natural inclination toward the timing of daily periods of activity and rest, reflecting the phase of their internal circadian clock. It is commonly described along a morningness–eveningness spectrum. Morning-type individuals, or larks, prefer earlier wake times and peak performance in the morning, while evening-type individuals, or owls, favor later schedules and higher alertness at night. Most people fall somewhere in between, and chronotype can shift with age and circumstances.

Measurement and classification typically rely on self-report questionnaires such as the Morningness-Eveningness Questionnaire (MEQ) or the Munich Chronotype Questionnaire (MCTQ), which estimate preferred timing of sleep and activities. Objective methods include actigraphy and measures of dim-light melatonin onset (DLMO). Chronotype exists on a continuum rather than as discrete categories.

Determinants and variation arise from genetic factors, age, sex, and environmental influences. Light exposure and social obligations entrain circadian rhythms, while adolescence tends to tilt toward later chronotypes and aging often shifts toward morningness. Irregular schedules, shift work, and jet lag can alter perceived chronotype or disrupt alignment with external demands.

Implications for health and daily life involve sleep quality, cognitive performance, mood, and metabolic risk. Misalignment between chronotype and work or school schedules can contribute to sleep debt and associated problems. Conversely, aligning routines with one’s chronotype or using light-based strategies can improve sleep timing and daytime functioning.

Management approaches include timed light exposure to advance or delay the circadian phase, maintaining consistent sleep-wake times, and adopting flexible scheduling in educational or occupational settings to reduce misalignment.