If you feel more sluggish during certain times of the day, it could be due to your sleep chronotype.

The chronotype affects the body’s natural tendency to be asleep or awake, according to the Sleep Foundation.  

Knowing and adapting to the ideal schedule for your sleep chronotype could improve your rest and help you accomplish daily tasks more efficiently, sleep experts say.

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“Your chronotype, or natural sleep-wake preference, refers to your natural tendencies to feel awake or sleepy at different times of the day,” Dr. Anne Marie Morse, a pediatric sleep medicine physician in Pennsylvania, told Fox News Digital.

There are four main types of sleep chronotypes: Bear, Wolf, Lion and Dolphin.

Genetics, age, geography and the body’s circadian rhythm (its internal 24-hour clock) can determine one’s chronotype, the Sleep Foundation said in its report.

In addition to sleep quality, chronotypes can also influence appetite, exercise and body temperature.

Breaking down the chronotypes

Dr. Michael Breus, Ph.D., a board-certified sleep specialist in Los Angeles, first introduced the four chronotypes based on sleep-wake patterns seen in certain animals.

“We’ve discussed early birds and night owls, but I’ve broken it down further into four categories based on other animals,” he told Fox News Digital. 

“Your chronotype, or natural sleep-wake preference, refers to your natural tendencies to feel awake or sleepy at different times of the day.”

“Each of these four chronotypes is defined by specific windows of productivity during which they function and perform at their best … at different times of day.”

Lion

Individuals who are considered the Lion chronotype typically wake up early (around 6 a.m.), are more productive in the morning hours and prefer to nap around 1:30 p.m., according to a report by Breus on his website. 

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Their energy begins to wind down in the early evening and they may struggle with socializing at night, according to Breus’ report. Bedtime is usually around 10 p.m.

An estimated 15% of individuals fall into this chronotype.

Bear

The Bear chronotype wakes up with the sun at around 7 a.m., functions well during traditional office hours between 10 a.m. and 2 p.m., and does not struggle with attending evening social activities.

This chronotype prefers to go to bed at around 11 p.m., according to the Sleep Foundation report.

Bears account for around 55% of individuals.

Wolf

Wolf chronotypes are similar to “night owls.” As the day winds down, these individuals’ energy levels rev up with a preferred bedtime at around midnight, Breus stated in his report.  

People in this category typically wake up around 7:30 a.m., are groggy in the morning and are most productive between the hours of 1 and 5 p.m., according to the Sleep Foundation.

About 15% percent of people are considered to be this chronotype.

Dolphin

Those in the Dolphin chronotype are usually light sleepers, have a hard time unwinding at bedtime, and rarely follow a consistent bedtime schedule, several sleep experts told Fox News Digital. 

Dolphins wake up at around 6 a.m., are most productive between the hours of 3 p.m. and 7 p.m., and go to bed at around 11 p.m.

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“Those with the Dolphin chronotype have difficulty following any sleep schedule due to disturbances like noise and light,” Morse told Fox News Digital. “Productivity is best in the late mornings to early afternoons.”

People struggling with insomnia are often Dolphin chronotypes, according to Morse.

Nearly 10% of individuals fall into this category.

How to determine your chronotype

To determine your chronotype, the Sleep Foundation recommends considering your sleep preferences, your energy levels throughout the day and when you eat your meals. 

Questionnaires such as the Morning-Eveningness Questionnaire (MEQ) and the Munich Chronotype Questionnaire (MCTQ) can help determine one’s chronotype.

Breus also developed an online chronotype quiz at SleepDoctor.com to help individuals determine whether they are a Bear, Wolf, Lion or Dolphin.

Understanding how your chronotype works can help you sleep better at night and feel more refreshed during the day, according to Breus.

Adjusting schedules based on chronotype

After pinpointing your chronotype, Breus recommends tailoring daily activities based on periods of peak energy and productivity levels.

“If you frequently experience poor sleep quality despite getting a full night’s sleep, you may be working against your chronotype,” he said.

Morse recommends that people schedule important tasks at times when they naturally feel most alert and to adjust bedtimes to fit their natural sleep patterns, rather than “powering through” schedules that don’t match their chronotypes.

For example, an individual who is categorized as a Lion should try to tackle large projects, important meetings or social activities earlier in the morning, when their tendency is to be most energetic and productive, the expert said. 

Since they are typically early risers, Morse said Lions should establish an early bedtime to ensure that they get enough sleep. She also advised Lions to avoid large meals or rigorous exercise in the late evening, which could delay sleep.

“If you are a naturally late riser, or a Wolf chronotype, forcing yourself to wake up too early may lead to sleep deprivation.”

“If you are a naturally late riser, or a Wolf chronotype, forcing yourself to wake up too early may lead to sleep deprivation and could negatively impact health,” Morse told Fox News Digital.

“Wolves are the most productive in the afternoon, so steer away from big morning plans for optimal performance.”

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Morse also suggested that Wolf chronotypes sleep in cool, dark and quiet bedrooms, using blackout curtains or a sleep mask to block out early-morning light.

Since Dolphin chronotypes do not usually follow a set sleep schedule, Morse recommends that they prioritize going to bed and waking up at the same time every day, even on weekends.

“If you’re having difficulty falling asleep or staying asleep at night, try to avoid naps during the day and avoid screen time at least 30 minutes to an hour before bed,” he suggested. 

For those who fall into the Bear chronotype, Morse suggests getting sunlight exposure immediately upon waking in the morning. In the event of an afternoon slump, he recommends opting for a short nap at around 2 p.m. instead of reaching for caffeine. 

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If daily obligations get in the way of adhering to ideal bedtime schedules, Morse said the best step is to try to gain better alignment.

Regardless of chronotype, the American Academy of Sleep Medicine recommends getting at least seven hours of sleep per night to support overall health and well-being.