A chronotype describes an individual’s natural inclination for when they prefer to sleep and wake up during a 24-hour period. It reflects a person’s inherent timing for peak alertness and activity, often referred to as their “internal body clock.” A chronotype is a behavioral manifestation of the body’s broader circadian rhythm, which is the internal biological process that regulates the sleep-wake cycle and other bodily functions over approximately 24 hours.
The Different Chronotypes
People fall into one of three main chronotypes: the morning type, commonly called a “lark,” the evening type, known as an “owl,” and the intermediate type. Morning larks naturally wake early, often before sunrise, and feel most energetic and productive in the early hours. They tend to go to bed early in the evening, with their energy levels gradually declining throughout the day. For example, a lark might find their best focus for demanding tasks between 7:00 AM and 12:00 PM, and prefer exercising in the morning.
Evening owls, in contrast, prefer to stay up late and wake later in the morning, often feeling sluggish upon waking. Their periods of peak alertness and productivity occur later in the day, extending into the evening. An owl might experience their creative surge or highest productivity around noon and again in the late evening, making those times ideal for complex work.
The majority of people, estimated to be between 60% and 70%, belong to the intermediate chronotype. These individuals do not exhibit a strong preference for either early mornings or late nights. Their sleep and wake times fall between those of larks and owls, with wake-up times around 7:00-7:30 AM and bedtimes between 11:00-11:30 PM. This intermediate group often finds flexibility in their daily rhythms, adapting more readily to varying schedules.
What Determines Your Chronotype?
An individual’s chronotype is influenced by a combination of genetic and environmental factors. Genetics play a substantial role, as chronotype is a heritable trait. Specific “clock genes,” such as PER3, are involved in regulating the body’s internal circadian clock. Variations in these genes can influence a person’s predisposition towards morningness or eveningness, with the PER3 gene associated with differences in light sensitivity and chronotype.
Age also impacts chronotype, causing shifts throughout a person’s life. Children often exhibit an earlier chronotype. During adolescence, there is a common shift towards a later chronotype, with teenagers becoming more evening-oriented. This trend reverses in older adulthood, as individuals shift back towards an earlier chronotype after approximately age 19.
Environmental factors, particularly light exposure, further shape the expression of one’s chronotype. Light is the primary cue that synchronizes the body’s internal clock with the external 24-hour day. Exposure to bright light in the morning can help reinforce an earlier chronotype, while evening light, especially from electronic devices, can delay sleep onset and reinforce a later chronotype. These external cues interact with genetic predispositions to fine-tune an individual’s natural sleep-wake patterns.
Living in Sync With Your Chronotype
Aligning one’s daily schedule with their natural chronotype can improve overall well-being and productivity. When there is a mismatch between a person’s biological clock and the demands of work, school, or social life, it can lead to “social jetlag.” This misalignment can result in sleep deprivation and jetlag-like feelings, affecting health and mental state. Night owls often experience more severe social jetlag due to societal schedules favoring early risers.
Working with your chronotype involves scheduling activities to coincide with your natural peaks of energy and alertness. For morning larks, this means tackling demanding intellectual tasks or physical activities in the early hours when their focus is highest. Conversely, evening owls can benefit from scheduling their most complex work or creative endeavors for the late afternoon or evening, when they naturally feel more awake and productive. For all chronotypes, maintaining a consistent sleep schedule, even on weekends, helps to minimize social jetlag and supports the body’s natural rhythm.