Learn Your Own Chronotype

Learn Your Own Chronotype
You may think you know whether you are a lark, an owl, or a hummingbird, but are you right?

You may have a pretty good idea about whether you are a lark, an owl, or a hummingbird. However, our ideas about ourselves sometimes mislead us. A famous example is the fact that in surveys, as many as ninety percent of people say that they are above-average drivers.

If you want a more objective look at your personal chronotype, you can use the same measure that researchers use: the AutoMEQ (automated Morningness-Eveningness Questionnaire), available here.

This tool asks questions about your behavioral preferences and abilities. For example, when would you go to bed, and when would you get up, if the choice were entirely up to you? The questionnaire takes no more than five to ten minutes to complete, and as soon as you finish, you get personalized feedback. Your final score will fall between 16 and 86. Low scores—40 or below—indicate owlishness, and high scores—above 58—indicate larkishness. Most people, roughly seventy percent, fall into the hummingbird category. These intermediate scores indicate that the person’s daily rhythm—sleep/wake cycle, alertness, energy—is in sync with local clock time.

Our chronotype questionnaire is not the only approach to measuring people’s chronotype. Scientists in Munich, Germany have focused on comparing sleep timing on work days and days off. In this method, daily habits and preferences about what to do when during the day are not the point. Instead, the research logs actual sleep times, and contrasts alarm-clock-driven wake-up on workdays with internal-clock dominance on days off. Owls, they find, get less sleep on workdays and longer recovery sleep on days off.
The questions on our chronotype questionnaire focus on your behavioral preferences, but the score you get indicates more than simply the way you like to schedule your daily activities.

In one study, we asked research participants to take the questionnaire, then to take samples of their saliva every thirty minutes during the four hours before their usual bedtime. They were also instructed to wear welder’s goggles throughout the evening. The goggles kept the amount of light reaching their eyes to a very low level.
The reason we required goggles has to do with the hormone melatonin. Normally, at some point during the evening, a person’s inner clock sends a nerve signal to the pineal gland, deep in the brain, to start producing melatonin for the rest of the night. The specific time at which this happens can vary from one person to another by as much as six hours or more. Once the pineal is activated, the hormone quickly shows up in the blood, and soon after in the saliva. A couple of hours later, you are ready to fall asleep.

However, if you are exposed to bright light during the time melatonin production ordinarily starts, the pineal gland will stay shut down, as it is during the daytime hours. This robs the body of an important signal for normal sleep onset. The bright light also raises energy levels and triggers a delay in the setting of the inner clock. Dim light, such as that filtered through the welder’s goggles, allows melatonin levels to follow their natural evening course toward bedtime and protects the inner clock from shifting later.
What did our study show? Based on their chronotype scores, we divided the participants into larks, owls, and hummingbirds. As we expected, the larks had melatonin levels that started rising as early as 7 PM. By around 9 PM, they were ready to go to sleep. For owls, however, melatonin did not show up in their saliva until much later, as late as midnight or 1 AM, and they were not ready for sleep until a couple of hours later still. So if you know your chronotype, based on our chronotype questionnaire, you also gain a good insight into the physiological functioning of your inner clock … and without the hassle of having to spit into a specimen jar every half hour!