Published On 4/7/2026
Do you find it difficult to wake up in the morning? The problem is not necessarily laziness. Your genes may be the reason, as they affect the natural biological pattern that regulates your sleeping and waking times, and determines your periods of activity and concentration during the day, which is known as the “chronotype” or the body’s time pattern.
What is a chronotype?
Chronotype is the body’s natural tendency to sleep at certain times, and what we commonly know as a “morning person” or “night owl.” This pattern not only determines sleep and wake times, but also affects appetite, exercise, and body temperature. It also explains a person’s feeling of alertness at certain hours of the day and sleepiness at other hours.
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Recent studies indicate that chronotype is strongly influenced by genetic factors. Research has shown that some variations in circadian genes, such as the PER3 gene, are associated with people’s tendency to wake up early or stay up late.
Some researchers believe that the diversity of sleep patterns among ancient humans helped hunter-gatherer groups survive, as some individuals remained awake to guard others while sleeping.
How do scientists define chronotypes?
Researchers have developed several questionnaires to find out whether a person tends to be active in the morning or evening, but they confirm that the chronotype is not limited to two categories, but rather falls on a broad spectrum in which most people belong to the middle region. The most famous of these tests are:
- Morning-Evening Questionnaire (MEQ) Which measures a person’s preferences through questions about sleep and wake times and daily activities, such as eating and exercising.
- Munich Chronotype Questionnaire (MCTQ) Which depends on actual sleeping and waking times in daily life, not just on subjective impressions.
Sleep expert Michael Brewis also developed a famous test that classifies people into 4 animal-inspired types – lion, bear, wolf, and dolphin – according to their sleeping and waking habits.
What is your chronotype?
The chronotype varies from one person to another depending on several factors, most notably genes and age, and some scientists believe that geographical location and the number of daylight hours may also play a role. To know your chronotype you can observe:
- The time you prefer to sleep and wake up when you are not imposed by alarms or work schedules.
- Peak hours of your mental or physical activity.
- Times during the day when you feel hungry or low on energy.
These classifications give a general picture of the style closest to each person, but they are not strict rules, as the body’s needs and biological rhythm differ from one individual to another.
The four chronotypes
Morning people are those who wake up early and reach their peak productivity in the early hours of the day, then their energy decreases in the evening and they tend to sleep early.
The most common pattern, as some estimates indicate that it includes about 55% of people. Its owners conform to the cycle of sunrise and sunset, and adapt easily to traditional work and study schedules.
People who prefer to stay up late and feel more active in the afternoon and evening represent about 15% of people. They often have difficulty adhering to morning schedules imposed by schools or workplaces.
It includes people with light or intermittent sleep, who have difficulty maintaining a regular sleep schedule, are often more sensitive to noise and light, and are more likely to have patterns of chronic sleep disturbances.
Chronotype and circadian rhythm.. What is the difference?
The chronotype is closely linked to the circadian rhythm, the internal biological clock that regulates the 24-hour sleep-wake cycle and other vital functions. However, there is an important difference:
- Circadian rhythm It regulates the timing of vital processes within the body, and can be relatively adjusted through exposure to light or adherence to a fixed sleep and wake routine.
- Chronotype The natural time in which the body prefers to sleep and wake up is determined within this rhythm, and is more closely related to the genetic makeup, so it is more stable and difficult to change radically and permanently.
The chronotype also changes with age; Children tend to wake up early, while the tendency to stay up late increases in adolescence, and then the pattern gradually returns to the morning with age.
When the chronotype conflicts with the requirements of study or work, a person may suffer from what is known as “social jetlag,” a condition similar to jetlag between time zones, and leads to fatigue, lack of concentration, and perhaps mood disturbance.
Why is it important to know your style?
Studies indicate that morning people, on average, perform better academically, while night owls tend toward creative thinking and unconventional solutions. But researchers point out that part of these differences is due to the nature of study and work schedules, which start early and do not take much consideration of nighttime patterns.
In contrast, other research has linked a nocturnal pattern to an increased odds of:
- Sleep disorders.
- Obesity and type 2 diabetes.
- Some mood disorders such as anxiety and depression.
- Unhealthy habits such as lack of physical activity, eating late, and excessive use of electronic devices at night.
However, researchers emphasize that these risks are not inevitable, but are also affected by the number of actual hours of sleep, lifestyle, and the extent to which work and study schedules match each person’s natural chronotype.
Can the chronotype be changed?
Some methods can help adjust the circadian rhythm and mitigate the effects of sleep schedule conflicts with the demands of daily life, including:
- Regulate exposure to natural light in the morning, and reduce exposure to bright lights and screens in the evening.
- Use melatonin supplements under medical supervision when needed.
- Improving sleep habits, such as setting bedtime and waking times as much as possible, and avoiding stimulants before bed.
But research indicates that changing the chronotype itself permanently is difficult, because it is linked to the structure of the body and its genes, even if it tends to change gradually with age. Therefore, experts advise trying to reconcile study and work commitments with the body’s natural pattern as much as possible, instead of engaging in a constant struggle with the body’s biological clock.
