## Introduction

People differ in whether they are more of a morning or an evening person. Many people are neither. What you are in this respect is your chronotype.

In daily life, morning types are also known as early birds and evening types night owls.

 The "Ch" in "Chronotype" is pronounced as a "k". "Chronos" means time in ancient Greek.

A much used chronotype scale is the Morningness-Eveningness Questionnaire (MEQ) by Horne and Ostberg (1976). That scale, however, has strict copyright rules and there are good alternatives.

The Circadian Energy Scale (CIRENS) is a two-item scale which correlates with the MEQ, but which is much shorter (2 vs 19 questions).

 Being short is a main benefit of the CIRENS, because typically, you want to combine the CIRENS with other questions or experiments. The less time people spend on one questionnaire, the less demanding the study is and the more time you may have for other important aspects of your study.

In the study by Ottoni and colleagues (2011), the CIRENS was tested with 225 college students (18-35 years). In their study, 17.3% were a morning type and 19.6% an evening type (and the rest neither).

### Why is it important?

Chronotype can be related to medical issues and performance. For example, children who are evening types might have difficulties with morning classes, as you can read here.

### Interpretation of the scores.

The CIRENS score ranges from -4 to 4.

Type scores Percentage of student in Ottoni’s study

Morning type

-4, -3, -2

17.3%

Neither type

-1,0,1

63.1%

Evening type

2, 3, 4

19.6%

 Example interpretations: if you score -3, you are a morning type, and if you score between -1 and 1 you are neither a morning nor an evening type.

## Run the demo

It seems that the CIRENS can be used for research, but you need to acknowledge the authors and their research paper when writing about it (Ottoni et al., 2011).

## Technically

This is a simple scale question. The calc type is used to calculate the score.

## The survey code for PsyToolkit

Copy and paste this code to your PsyToolkit account if you want to use the scale in your own online research project
```scale: energy
- very low
- low
- moderate
- high
- very high

l: cirens
t: scale energy
o: boxes
q: In general, how is your energy level in the morning and in the evening?
- In the <b>morning</b>
- In the <b>evening</b>

l: score
t: set
- calc \$cirens.2 - \$cirens.1

l: feedback
t: info
q: Your Cirens Score is {\$score}.<br><br>
A score of -2 or lower means you are a morning type.<br>
A score of 2 or higher means you are an evening type.<br>
A score in between means you are neither.<br>```

I strongly recommend to read the review of the chronotype personality by Ana Adan and colleagues (2012) as well.

An interesting open-access article on the genetics of chronotypes was published in 2019 in Nature (Jones et al. (2019)). This study argues that there is a link between chronotype and mental health. For example, being a morning person is associated with a higher degree of subjective well-being.

Sex differences in chronotype are not frequently studied, but there is one high profile study from 2020 (Kim et al. (2020))

## References

• Reference to the original MEQ: Horne and Ostberg (1976). A self-assessment questionnaire to determine morningness-eveningness in human circadian rhythms. International Journal of Chronobiology, 4, 97–110.

• Ottoni, G.L., Antoniolli, E., & Lara, D.R. (2011). The Circadian Energy Scale (CIRENS): Two Simple Questions for a Reliable Chronotype Measurement Based on Energy. Chronobiology International, 28, 229-337.

• Ana Adan, Simon N. Archer, Maria Paz Hidalgo, Lee Di Milia, Vincenzo Natale & Christoph Randler (2012) Circadian Typology: A Comprehensive Review, Chronobiology International, 29:9, 1153-1175, DOI: 10.3109/07420528.2012.719971

• Jones, S.E., Lane, J.M., Wood, A.R. et al. Genome-wide association analyses of chronotype in 697,828 individuals provides insights into circadian rhythms. Nat Commun 10, 343 (2019). https://doi.org/10.1038/s41467-018-08259-7

• Kim, K.M., Han, S.M., Heo, K. et al. Sex differences in the association between chronotype and risk of depression. Sci Rep 10, 18512 (2020). https://doi.org/10.1038/s41598-020-75724-z. Open access