First off, what the heck is a “chronotype,” you ask? Excellent question!
The Definition of “Chronotype”
Chronotype = “A person’s natural inclination with regard to the times of day when they prefer to sleep or when they are most alert or energetic.”
Chronotype vs. Circadian Rhythm
Here is a concise explanation (and a link to a great podcast episode if you’re interested in more information) from a Bulletproof blog post:
“Your circadian rhythm — your brain’s sleep-wake cycle — determines when you’re alert and when you’re sleepy over a 24-hour period. It’s the internal clock that your brain uses to signal when to release certain hormones. While working with insomnia patients, Dr. Breus observed that everyone’s circadian rhythm is slightly different. (He details his fascinating findings, particularly about so-called insomniacs, on an episode of Bulletproof Radio.) . . . When Breus switched up his patients’ daily routines to accommodate their sleep chronotype, their productivity soared and several sleep issues resolved.”
Thus, one’s circadian rhythm and chronotype are not the same, but they are intrinsically related. Everyone possesses a circadian rhythm, but circadian rhythms differ from person to person. These differences are explained by individual chronotypes.
Why does your chronotype matter?
As mentioned above, knowing your chronotype can help you to maximize your daily routine and efficiency.
Evolutionarily speaking, it was important for group members to be alert and 100% awake at different times of day. If a certain group possessed only morning types, for example, it would be at higher risk of invasion in the evening since all group members would have (likely) fallen asleep early. Therefore, researchers have determined that “. . . asynchronous periods of wakefulness provide an opportunity for vigilance when sleeping in groups . . . Chronotype variation and human sleep architecture (including nocturnal awakenings) in modern populations may therefore represent a legacy of natural selection acting in the past to reduce the dangers of sleep.”
Currently, society is structured in a manner that favors morning types. Most jobs require workers to rise early and be 100% “on” beginning around 9am. Further, most schools require students to begin learning around 8am. However, many humans–adults, kids, and teenagers alike!–are evening types. Since the status-quo favors early risers, evening types are often viewed as “lesser” and/or “abnormal.”
When considering the reality that both morning and evening types were valued as being beneficial, and necessary in tribal societies, society’s favoritism of morning types has led neuroscientists to advocate for their evening type counterparts. If you’re one of the lucky ones who can choose your own work schedule, you should not feel inadequate if you prefer to get a later start to the day. Or, if you’re an evening type (E-type) who is forced to wake up early Monday through Friday, you should know that “. . . E-types accumulate a sleep deficit during weekdays due to social and academic commitments and that they recover from this deficit during ‘free days’ on the weekend.”
I am an evening type who anxiously anticipates lazy weekend mornings, but I’ve often been chastised for this. Now, knowing my chronotype, I feel vindicated!
How do you know which chronotype you are?
Chances are you can classify yourself as a morning or evening type without taking a quiz, but sleep specialist Michael Breus, PhD, developed a free online quiz based on his research and best-selling book The Power of When. Breus more specifically categorizes morning and evening types into four groups: dolphins, lions, bears, and wolves.
After taking the quiz, you can use your newfound knowledge to consider the most optimal routine for your chronotype.
If the schedule of your current job and/or lifestyle doesn’t allow you to optimize your chronotype (mine doesn’t!), you can at least be mindful of your body’s natural inclinations in order to enhance your free time on weekends and vacations . . . without feeling guilty, weird, or lazy!
I’m a “wolf,” but I must wake up early each morning (like most members of modern society) to get to work. Since I need to wake up so early, I must also force myself to go to bed earlier than I’d like. The key word in that sentence is “force”; it’s difficult for me to fall asleep early, so I end up accumulating “sleep debt.” On weekends and vacations, then, I’ve learned to embrace my chronotype by sleeping in, staying up later, and reversing unwanted sleep debt. I used to feel guilty and lazy when I’d sleep in, but now I realize that sleeping in helps me to optimize my health. I think it’s great for every person to pinpoint his or her chronotype, but it’s especially liberating for us wolves who are often pressured to wake up early since our society values early risers!
What are your thoughts on chronotypes? As always, I love to read any and all comments you may have!
In each blog post, I aim to bring you food for thought (pun intended. Note: my day job is teaching English), but don’t take my word for it! Click on and read all of the links above to become your own expert on this topic; knowledge is power. The more you know and understand the “why” behind each biohack, the easier it will be to stick to it and realize you can’t live without it!