Composite scales of morningness andpreferences: Preliminary validity data in
Peruvian undergraduates
J. F. DIAZ-MORALES* and M. P. SANCHEZ-LOPEZ
Departamento de Psicologıa Diferencial y Psicologıa del Trabajo, Facultad de Psicologıa,
Universidad Complutense de Madrid, Campus de Somosaguas, s/n, 28223, Madrid,
Spain
The aim of this study is to offer preliminary results about the validity of the
composite morningness scale (CS) and the early/late preferences scale (PS) in
a Peruvian sample. The relationship of both scales with the preferred rising
and retiring times was analysed, along with the level of self-reported
alertness. In Bohle et al.’s (2001) work, the relationship between morningness
and preferred rising and retiring times was higher over the weekend than on
weekdays. This difference explained the dispositional nature of morningness,
due to the possible lesser influence of time schedules over the weekend in
individuals’ preferences. This result is replicated in a group of 139 Peruvian
undergraduates, aged between 18 and 29 years (M=21.73), of whom 78.4%
were women. The relationship between morningness and (actual) normal
rising and retiring times on weekdays and over the weekend is considered.
The results partially confirm Bohle et al.’s (2001) hypothesis about preferred
rising and retiring times and their relationship with the PS, and actual rising
time and its relationship with the CS and PS. The differences in the level of
self-reported alertness between morning, intermediate and evening-oriented
groups provide support for the validity of both scales. Finally, the scores of
CS and PS in Peruvian undergraduates are similar to those found by Smith et
al. (2002) in university students from six countries.
Keywords: Morningness – eveningness; Time-of-day; Actual and preferred
wake – sleep behaviour; alertness.
1. Introduction
Freeman and Hovland (1934) and Kleitman (1939) indicated that most people can be
differentiated along a continuum ranging from low morningness (or high eveningness) to
high morningness (or low eveningness). At this time, in the 21st century, Natale and
Cicogna (2002) analysed data to determine whether morningness – eveningness is really a
*Corresponding author. Email: [email protected]
Ergonomics, Vol. 48, No. 4, 15 March 2005, 354 – 363
ErgonomicsISSN 0014-0139 print/ISSN 1366-5847 online # 2005 Taylor & Francis Group Ltd
http://www.tandf.co.uk/journalsDOI: 10.1080/0014013042000327661
continuum, finding that the differential characteristics of morning and evening-oriented
individuals emerge, without necessarily taking into account the extreme ‘types’ (clearly
morning or evening orientated).
Individual differences in the circadian rhythm are the underlying mechanism of this
continuum (Kerkhof 1985). Circadian rhythms are cycles of approximately 24 h that have
been identified by analysing biological variables (for example, body temperature and levels
of hormone secretion) and also by studying behavioural variables, such as performance of
various tasks, mood or physical exercise (Folkard and Monk 1985; Smith et al. 1997). It is
considered that preference for performing activities at different times of day, mainly in the
morning or in the evening, is a reliable index of these individual differences in circadian
rhythm (Kerkhof 1985). This individual difference in circadian variability is called
morning vs. evening orientation or, more simply, ‘morningness’. Thus, the creation and
adaptation of scales or inventories to determine people’s circadian orientation has been
the focus of much of the research in this area, as the use of applied questionnaires (e.g. for
personnel selection for night shifts) seems more practical than other more rigorous
assessment procedures (for example, assessment of rectal temperature, hormone level in
blood, etc.), which are not very practical because of their high cost.
The most well-known questionnaire is the one created by Horne and Ostberg (1976),
the morningness – eveningness questionnaire (MEQ). Subsequently, other questionnaires
were developed, such as the circadian type questionnaire by Folkard et al. (1979), the
diurnal type scale (DTS) by Torsvall and Akerstedt (1980), or the Mauburger
questionnaire (Moog 1981). In order to obtain a reliable and valid measurement of
morningness that would overcome the psychometric deficiencies of the former scales,
Smith et al. (1989) created the composite scale of morningness (CS) using the best items
from the MEQ and the DTS. Other proposals have subsequently appeared: the reduced
version of the MEQ (Adan and Almirall 1991); the morningness scale adapted to persons
with an elemental reading level (basic language morningness scale, BALM), which is a
simplified version of the CS (Brown 1993); the early/late preferences scale (PS) created by
Smith et al. (1993) to improve some aspects of the CS; or the lark – owl chronotype
indicator (LOCI) by Roberts and Irvine (1999).
The CS has been translated into French (Caci et al. 1999), Thai (Pornpitakpan 1998,
2000) and Italian (Natale and Alzani 2001). Studies with Spanish (Martın 1989, Dıaz
Ramiro 2000, Dıaz-Morales and Aparicio 2003, Dıaz-Morales and Sanchez-Lopez 2004,)
and Argentine populations (Sanchez-Lopez and Dıaz-Morales 2001) have revealed
adequate reliability of the CS. In the Peruvian population, Dıaz-Morales et al. (2005) also
obtained satisfactory psychometric indices. In general, the results of these studies indicate
that the CS can be used in Spain, Argentina and Peru insofar as reliability (internal
consistency) is concerned. However, its validity has not yet been evaluated, although this
aspect has been sufficiently addressed in other languages (Smith et al. 1989, Greenwood
1994, Guthrie et al. 1995).
Smith et al. (1993) created the PS to resolve some of the problems of the CS; the use of
different response scales in some of the items and the inconvenience of referring to specific
times of day. Therefore, the PS, which has a more consistent and less complex response
format, is more appropriate to assess the morningness of people who have atypical or
irregular sleeping habits.
Currently, the CS and the PS are considered to be two of the most reliable and
valid scales to measure morningness (Bohle et al. 2001, Smith et al. 2002, Zickar et al.
2002). Bohle et al. (2001) analysed both scales in a sample of university students,
concluding that neither of them is clearly superior as far as psychometric properties
Composite scales of morningness and preferences 355
(internal consistency and temporal stability) are concerned. Smith et al. (2002) tested
the hypothesis of equality of factor form and factor loadings of the CS and the PS in
six countries. The results indicate an invariant bifactor structure for both scales, which
allows comparison of the means in the morningness factors in each of the countries
studied. In addition, both scales showed adequate psychometric indices (reliability and
validity) in the six countries. Zickar et al. (2002) studied the discrimination capacity of
the items from the two scales. Most of the items have very acceptable and useful
indices for differentiating morningness from eveningness orientation. Both the scales
are adequate when their items are analysed from the viewpoint of item response
theory. However, the items about preferred rising time are more closely related to the
latent morningness construct than are items that assess peak performance or retiring
time.
University students have participated in most of the studies that analyse the
psychometric properties of the scales to assess morningness – eveningness. The
university population is adequate because their circadian rhythms are not so much
under the influence of time schedules and social patterns as those of the adult working
population. Most occupations involve dedicating a large part of the day to work,
which affects life habits and, as has been noted in various studies (Mecacci and Zani
1983, Park et al. 1997), produces a higher tendency toward morningness. According to
Bohle et al. (2001), when university students are asked about their preferred rising and
retiring times (‘if you were totally free to choose’), a difference between these wake –
sleep behaviours on weekdays and over the weekend can be established. The latter are
‘free’ from the possible influence of study or work schedules. Therefore, as
morningness is considered a disposition, it is not surprising to find that sleeping
preferences over the weekend are more related to morningness. The first objective of
this study was to examine if the greatest relationship showed by Bohle et al. between
morningness and preferred rising and retiring times during the weekend was also
found with normal (actual) rising and retiring times. The second research objective
was to analyse the relationship of the CS and the PS with the level of perceived
alertness, one of the variables with which morningness has the highest relationship
(Kerkhof 1985).
2. Method
2.1. Participants
One hundred and thirty-nine students from the city of Lima (Peru) participated in this
study. There were 109 (78.4%) women and 30 (21.6%) men. The mean age was 21.73
years (SD=2.63, range=18 – 29). Most of the students attended classes at different
times of the morning or the afternoon, without having a strict study schedule.
2.2. Measurement instruments
2.2.1. Composite scale of morningness (Smith et al. 1989). The CS is a 13-item scale
with a Likert-type response format. Five of the elements of the scale refer to different
times of the day. The score is obtained by the sum of the items and ranges from 13
(extreme eveningness) to 55 (extreme morningness). Greenwood (1994), Guthrie et al.
(1995) and Smith et al. (1989) provide adequate data about both reliability and
validity. The CS was translated into Spanish by Dıaz Ramiro (2000). This version was
356 Juan F. Dıaz-Morales and Marıa P. Sanchez-Lopez
used on a sample of university students and adults, revealing excellent psychometric
properties: Cronbach’s a coefficient of 0.90 and a high correlation (r=0.79) with the
MEQ by Horne and Ostberg (1976). In subsequent studies, its reliability and validity
have been corroborated for Spanish-speaking populations. For example, an acoefficient of 0.75 was obtained in the Argentine population (Sanchez-Lopez and
Dıaz-Morales 2001), and an a of 0.85 was obtained in the Spanish population (Dıaz-
Morales and Sanchez-Lopez 2004).
2.2.2. Early/late preferences scale (Smith et al. 1993). The PS is made up of 12 items that
do not refer to specific times of day, but to persons’ preference for performing various
activities, and comparing them with their reference group. The score of this scale is
calculated by adding all the items, and ranges from a minimum of 12 (extreme
eveningness) to a maximum of 60 (extreme morningness). In addition to the 12 elements
that comprise the scale, two items have been included: ‘In general, when do you feel most
active?’ and ‘In general, when do you feel at your best?’ The response scale of these two
items is the same as for the remaining elements of the PS. These items were included by
Bohle et al. (2001) and are used in the current study for comparative purposes. The PS
was translated into Spanish by the authors of this study. A pilot study was carried out
with a group of university students who analysed item wording and comprehensibility.
An a coefficient of 0.83 was obtained by Dıaz-Morales and Sanchez-Lopez (2004) in an
undergraduate population.
2.3. Other measurements: Sleeping behaviour and subjective alertness level
As morning and evening types differ in their sleeping habits (Kerkhof 1985),
participants were asked to indicate their preferred and habitual rising and sleeping
behaviour on weekdays and over the weekend. In addition, participants had to
estimate how alert they felt on a day when they had no important responsibilities.
Ratings were provided at 2-h intervals, from 06:00 until 02:00, on a 9-point Likert-
type scale (higher scores indicate a higher level of alertness). ‘Subjective alertness is
probably the most powerful and repeatable of all the circadian rhythms of
psychological process’ (Natale and Cicogna 1996) and, therefore, it is the best
criterion to use as evidence of the external validity of morningness and was included
in this study to compare the results with those obtained by Bohle et al. (2001).
According to Bohle et al. and Smith et al. (2002), these measurements are additional
indicators of morningness – eveningness and are used as a preliminary assessment of
the validity of the PS and CS.
2.4. Procedure and data analysis
The scales were administered by the first author during the students’ normal classes in the
month of June. Administration was carried out in groups; some groups were assessed in
the morning and others in the afternoon. Participation was voluntary and participants
were informed about their results. The data were analysed by means of basic descriptive
statistics (e.g. means, standard deviations and cut-points). Scale normality was analysed
by means of the Kolmogorov-Smirnov test. Student’s t-test was used to calculate gender
differences across groups and Pearson’s correlation to analyse the relationships between
morningness and sleeping behaviours. Data analyses were carried out with the SPSS 11.5
statistical package.
Composite scales of morningness and preferences 357
3. Results
3.1. Descriptive statistics
The group mean for the CS was 33.88 (SD=6.24, range=16 – 51). The distribution of
the scale was normal (Kolmogorov-Smirnov’s Z=0.76, p=0.61). The group mean of
the PS was 35.02 (SD=7.09, range=15 – 54) and its distribution was normal
(Kolmogorov-Smirnov’s Z=0.92, p=0.35). No gender differences were observed either
in the CS (t (137)=0.83, p=0.403), or in the PS (t (137)=0.86, p=0.387). The scales
were highly correlated (r=0.83), which suggest that there is considerable overlap
between them.
The Peruvian university students showed very similar scores to those obtained by
Smith et al. (2002) for the CS in a group of Spanish university students (M=33.9,
SD=5.8), and much lower than those obtained by Colombian university students
(M=42.4, SD=5.7). The same tendency was observed in the PS: the Peruvian
university students showed similar values to those obtained by Smith et al. in a group of
Spanish university students (M=36.4, SD=6.0) and to those obtained by Bohle et al.
(2001) in Australian university students (M=35.1, SD=7.1), but a lower tendency
towards morningness than the Colombian university students (M=39.4, SD=6.2).
3.2. Relationships with other measurements
The correlation between morningness and perceived level of arousal (‘feel most active’)
was similar in both scales (r=0.63 and 0.58 for the CS and the PS, respectively), as was
the relationship between morningness and ‘feeling at one’s best’ (r=0.62 and 0.67 for the
CS and the PS, respectively).
Tables 1 and 2 show the results obtained in this study and those found by Bohle et al.
(2001). All the correlations were significant (p5 0.001), except for the correlations
between preferred and actual rising times on weekdays and the PS in the present study.
When performing the same comparison as Bohle et al. (2001), a higher relationship was
found between morningness and the preferred rising and retiring times over the weekend
than on weekdays for the PS ( – 0.47 and – 0.31 for rising and retiring times over the
weekend vs. – 0.38 and – 0.14 on weekdays, respectively). The CS showed a similar
relationship with the preferred rising time on weekdays and over the weekend ( – 0.58 and
– 0.60, for weekdays and weekends, respectively) and, in contrast to the results of Bohle et
Table 1. Comparison of the correlations of the composite morningness scale (CS) and theearly/late preferences scale (PS) and preferred rising/retiring times on weekdays and over the
weekend obtained in the present study and in Bohle et al. (2001)
Weekdays Weekends
Preferred rising time Preferred retiring time Preferred rising time Preferred retiring time
Scales
Present
study BohleaPresent
study BohleaPresent
study BohleaPresent
study Bohlea
CS – 0.58 0.45 – 0.36 0.40 – 0.60 0.68 – 0.19 0.52
PS – 0.38 b 0.43 – 0.14 0.39 – 0.47 0.65 – 0.31 0.49
a In Bohle et al. (2001), higher scores indicated eveningness orientation. Therefore, their correlations are
positive, whereas those from the present study are negative.b Except for this correlation, the remaining correlations were significant at p5 0.001.
358 Juan F. Dıaz-Morales and Marıa P. Sanchez-Lopez
al., a lower correlation with the preferred retiring time over the weekend ( – 0.36 vs. – 0.19,
for weekdays and weekends, respectively). The CS revealed somewhat weaker relation-
ships than those found by Bohle et al. (2001) (except for the relationship with preferred
rising time on weekdays). The correlation between the PS and the preferred retiring time
on weekdays was the weakest.
Following Bohle et al.’ s (2001) hypothesis, which considers morningness a
dispositional variable and predicts higher correlations with preferred waking and
sleeping preferences over the weekend, the participants were asked two more questions
about their actual rising and retiring times on weekdays and over the weekend (see table
2). The correlations between both the CS and the PS and the students’ actual rising times
were higher over the weekend, whereas the correlations of the scales with actual retiring
times were similar on weekdays and over the weekend.
Bohle et al.’s (2001) hypothesis seems to be confirmed for the PS and preferred rising
and retiring times over the weekend (vs. on weekdays), and for both the CS and the PS in
regard to the actual rising time over the weekend (vs. on weekdays).
3.3. Relationship with perceived alertness level
Figure 1 displays the levels of alertness of morning, intermediate and evening ‘types’
during waking hours, using the 10th and 90th percentiles of the CS (25 and 42
respectively). The morning group reported a higher level of alertness in the 08:00 – 10:00
interval and a progressive decrease beginning in the 18:00 – 20:00 interval. The evening
group reported their highest subjective alertness level during the 20:00 – 22:00 interval,
with an increasing pattern starting at the 14:00 – 16:00 interval. When the scores obtained
on the PS (percentiles 10th and 90th are 26 and 43, respectively) are used to establish the
three ‘chronotypes’, the same tendencies and maximum and minimum values emerge as
for the CS, although the intermediate and morning groups are not so differentiated as
when using the CS (see figure 2).
4. Discussion
This study provides new data about the validity of the PS and the CS. The results
obtained in the Peruvian population are similar to those found by Bohle et al. (2001) in
Australian university students and by Smith et al. (2002) in university students from six
countries. The mean values on the morningness scales are within the ranges found by
Smith et al. with very similar variability as indicated by the standard deviations.
The validity of both scales in the Peruvian population is adequate. The relationship
between the scales is higher than the range of correlations found by Smith et al. (2002) in
six countries (r=0.69 – 0.82), and is similar to the value obtained by Zickar et al. (2002)
Table 2. Correlations of the composite morningness scale (CS) and the early/late preferencesscale (PS) and actual rising/retiring times on weekdays and over the weekend
Scales Weekdays Weekends
Rising time Retiring time Rising time Retiring time
CS – 0.37 – 0.47 – 0.63 – 0.45
PS – 0.17a – 0.31 – 0.46 – 0.34
aExcept for this correlation, the remaining correlations were significant at p5 0.001.
Composite scales of morningness and preferences 359
Figure 1. Alertness ratings by time of day for the composite scale of morningness.
Figure 2. Alertness ratings by time of day for the early/late preferences scale.
360 Juan F. Dıaz-Morales and Marıa P. Sanchez-Lopez
(r=0.87). The results of Bohle et al. (2001) concerning morningness and preferred rising
and retiring times on weekdays and over the weekend have been partially replicated. They
are similar to those found by Bohle et al. for the PS, but not for the CS. One possible
explanation is that some items of the CS (e.g. social activities and meeting friends or
evening meal) can be ‘strongly influenced by social and cultural expectations, and less by
biological or behavioural disposition as morningness’ (p. 896). The PS, whose items do
not refer to specific times of day but rather to a comparative judgment, may be more
related to a dispositional variable such as morningness.
Participants were also asked to indicate their actual rising and retiring times on
weekdays and over the weekend. The results only support Bohle et al.’s (2001) hypotheses
regarding the CS and the PS for rising time. In this case, when taking the actual times into
account, a higher relationship between morningness and rising time over the weekend is
observed. Koscec et al. (2001) indicated that, assuming more freedom for university
students to organize their habitual activities, actual behaviour may reflect morningness or
eveningness to a greater extent than intentions or preferred behaviours. The 12 items
from the student MEQ, created by Koscec et al., refer to daily habits and usual
behaviours, more than to preferred habits or behavioural intentions.
The importance of the actual rising time and its relationship with morningness was
revealed by Zickar et al. (2002), who verified that items referring to the time when people
wake up in the morning differentiate morningness and eveningness orientation better
than do items referring to when people retire or to peak performance. These authors
postulate that it may be appropriate to add items to the PS referring to the time a person
wakes up in the morning. The importance of this type of behaviour is also emphasized by
Natale and Cicogna (1996), who conclude that, in order to differentiate morning and
evening-oriented persons, the transition from sleeping to waking is more representative
than the transition from waking to sleeping when considering alertness. The distinction
between actual and preferred habits should be considered in future studies, using another
type of non-university population, in which the influence of external social factors (e.g.
work schedules) on the relationship between actual/preferred habits and morningness is
analysed.
The differences between morning-, intermediate and evening-oriented groups in
perceived level of alertness are very similar to those found by Bohle et al. (2001) and by
Smith et al. (2002). Morning-oriented groups are more alert in the morning than are
intermediate and evening-oriented groups, whereas the latter reach peak alertness in the
afternoon. It was found that the pattern of perceived level of alertness over the day
(specifically, during the afternoon) is more similar in morning- and intermediate-oriented
groups when using the PS. This may be due to the reduced number of participants in this
study. Nonetheless, the authors consider that these results are in accordance with those
obtained by Bohle et al. and Smith et al. with a higher number of participants.
Lastly, the mean levels of the CS and the PS were compared with the results obtained in
other university groups from various countries, assuming that both scales measure a
unidimensional construct of morningness. The findings suggest that cultural differences in
circadian variation seem to exist, but the explanation of these differences is more complex
than the consideration of measures not referring to specific times (e.g. PS). The mean
scores in CS and PS are similar between Peruvian and Spanish undergraduates of Smith
et al. (2002), but very different from Colombian students. However, recently, other results
in a Spanish population were obtained (Dıaz-Morales and Sanchez-Lopez, 2004). The
undergraduates taking part in this study showed a greater tendency to eveningness
(M=28.9 for CS and M=33.5 for PS) compared with the Spanish subsample used by
Composite scales of morningness and preferences 361
Smith et al. Future research must clarify these discrepant results in a Spanish population.
A further issue is to determine whether the structure of the scales is identical in the
various countries compared, as stated by Smith et al. (2002). If the factor structure is
invariant in different countries, then one could compare the results obtained, knowing
that the compared factor(s) are identical in both populations and, therefore, comparable.
However, this does not invalidate taking the total score of the CS into account, as was the
case in the current study and in previous works (e.g. Greenwood 1994, Pornpitakpan
1998, 2000). Future studies should nonetheless address this issue, also taking into account
other aspects of the validity of the scales, such as their predictive validity and the
influence of social factors.
Acknowledgements
The authors thank Professors Cecilia Thorne, Karem Dıaz, Doris Argumedo and Monica
Iza who made the data collection during the research stay of the first author.
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