Have you ever noticed that some people wake up beaming before sunrise, while others don’t seem to shine until evening hours?
It’s not simply preference or habit – how and when we sleep is actually managed by genetics to some degree. Called phenotypes in the science world, see how these biological preferences work and what they mean for you.
What is a Sleep Phenotype?
A phenotype in genetics is a set of observable characteristics that result from the interaction of one’s genotype (instructions carried with genetic codes) with the environment.
It basically refers to how genetic information is expressed in reality. Phenotypes are the observable things like eye color, hair color, height, shoe size, some behaviors and other traits.
Now in terms of sleep, studies have confirmed a significant heritability of usual bedtimes, sleepiness and sleep duration with links to genes that regulate various components of the circadian clock.
Sleep phenotype (also known as chronotype) refers to an observable pattern of behaviors with genetic links, in this case, tendencies toward earlier bedtimes and wake times or later bedtimes and wake times, and schedules in between.
Health & Habits: What Sleep Phenotypes Mean for You
Researchers are interested in phenotypes for the insights they can provide on behaviors, health, and other related or associated expressions.
You don’t need genetic testing to figure out your sleep phenotype – simply consider your sleep habits and normal schedule. Think about when you naturally fall asleep and wake up when you aren’t using an alarm clock or don’t have to get up at a specific time for work or school.
Several studies have linked sleep habits with specific traits or health concerns, which can be helpful to know about. Read on to see what research has found regarding early and late sleep phenotypes.
The early phenotype or “lark” naturally goes to sleep earlier, around 9 to 10 pm, and wakes earlier, around 4 to 6am.
Habits of Early Birds:
- Your energy levels and productivity are highest in the morning to late morning.
- You might find it hard to do intense tasks late at night or work evening shifts.
- Early birds are more likely to be logical and analytical and favor concrete information sources according to a University of Madrid study.
- Early birds are also more proactive, translating into habits like getting better grades and thus better employment opportunities, according to a German study.
Early Birds & Health:
- Morning people tend to be happier, more positive and report feeling healthier, according to a University of Toronto study.
- People are more likely to become early birds with age due to biological changes and health issues.
- You’ll likely feel best exercising early in the morning.
Famous Early Birds:
- Composer Beethoven
- Apple CEO Tim Cook
- Avon CEO Andrea Jung
- Starbucks CEO Howard Schultz
- President George HW. Bush
- President George W. Bush
- Author Ernest Hemingway
- French Emperor Napoleon
- Author John Grisham
Late phenotypes or “night owls” naturally sleep later, around 12 to 4 am, and wake later, around 8 to 12 pm.
Habits of Night Owls:
- Your energy levels and productivity are highest in the afternoon to early evening hours.
- You might find it hard to wake up for early morning jobs, workouts or classes.
- Night owls are more likely to be imaginative and creative according to the Madrid study. Another study found that night owls scored higher on tests of creativity than intermediate or early types.
- People with higher IQs are more likely to be night owls, however night owl students also tend to perform worse academically compared to larks.
- An Australian study found that night owls were more likely show the “Dark Triad” of personality traits: Machiavellianism, narcissism and psychopathy. The psychologist behind the study also said night owls were more prone to darker behaviors like cheating, risk taking and were more prone to depression, dishonesty and boom-bust work patterns.
- Night owl-ism is common among teens, whose sleep schedules may gradually shift later, at least temporarily, during adolescence.
Night Owls & Health:
- Teens who sleep later on school nights (after 11:30pm) get less sleep and more likely to suffer emotional distress and poorer academic performance than earlier sleeping peers, according to a large-scale data study conducted by University of California Berkeley researchers.
- Late risers may be more prone to weight gain and are more likely to be overweight.
- Late risers are more likely to have more pain.
- Night owls are more likely to suffer depression and sleep problems, especially women and older evening types.
- You’ll likely feel best exercising in the evening.
Famous Night Owls:
- Soviet Union Leader Joseph Stalin
- British Prime Minister Sir Winston Churchill
- President Barack Obama
- President Bill Clinton
- Singer Elvis Presley
- Inventor Thomas Edison
- Author J.R.R. Tolkien
- Artist Henri de Toulouse-Lautrec
- Scientist Charles Darwin
If neither night owl or lark describes you, then you’re actually quite normal, so no worries! It’s thought that only around 20% to 40% of people fall in either extreme night owl or lark categories. The majority of people fall in the middle, or have slight preferences for late or early schedules.
In terms of trying to change sleep habits, we can’t quite change genetics but there are things people can do to normalize or improve sleep hygiene for better health.
For example, if you are a night owl that struggles to wake up early, you can start sleeping earlier by ensuring your bedroom is free of distractions, avoiding evening caffeine, keeping lights and electronics to a minimum in the evening, and sticking to consistent sleep and wake times even on the weekends.
Or if you are an early bird that yawns through the evening shift, you could try gradually shifting your sleep and wake times forward, use light blocking shades, and take naps if needed to ensure you are getting enough rest.
A recent Salk Institute study identified the master gene responsible for sleep and wake cycles, the Lhx1 gene, and other recent studies have also identified genetic links to sleep habits. These discoveries could open the possibility of solving sleep problems and adjusting rhythms, which could be interesting in the future.
Share: Do you find the personality traits for you sleep phenotype accurate? Anything surprise you?