original article
Sleepiness and inadequate bodily posture in classroom:
does laziness intermediate a relationship?
Sonolência e postura corporal inadequada em sala de aula:
a preguiça intermedeia a relação?
Luciana Marques Barros1, Katsumasa Hoshino2
Abstract
Objective: Sleepiness and naps occur in classrooms everywhere in
the world. Poor seating posture is also common in classrooms. Even
though poor posture causes students to be at risk for developing problems in the vertebral column, the relationship between sleep deprivation and bad postures has not yet received attention. Present study
evaluated the viability of such hypothesis of link and tried to disclose
other possibly involved factors. Methods: Twenty physicians, ten of
whom were orthopedists, evaluated the possible risk to the vertebral
column of 23 seating postures depicted in photos. Thirty-two skilled
teachers testified they had frequently detected the occurrence of those
postures displayed in the photos evaluated with the highest risk. Results: According to them, habit (90%), sleep deprivation (24%) and
laziness (11%) are the main causal factors of these postures. Interviews
carried-out with 50 scholars, 8 to 14 years old, both sexes, revealed
that part of them has sleep debit frequently and gave additional information confirming it. Sleepiness during lessons was reported by 39
(78%) among 50 students and 22 (44%) of them said to have slept at
least once during lessons. Sleepiness and laziness in the day following
sleep reduction was recognized by 96% of the students, and 92% reported to sit differently on those days. Conclusion: The obtained data
seems to grant the pertinence of the hypothesis that sleep deprivation
can be correlated to high risk bodily postures in classrooms and allows
us to hypothesize about laziness involvement in this relationship.
Keywords: sleep deprivation; posture; sleep stages; schools; human
body; spine/physiology; low back pain/diagnosis; arousal/physiology;
human; child.
RESUMO
Objetivo: A sonolência e as sonecas ocorrem nas salas de aula do
mundo todo. Modos inadequados de ficarem sentados nas salas de
aula também são comuns. Apesar de elas poderem ser prejudiciais por
serem fatores de risco para o desenvolvimento futuro de problemas
na coluna, a relação entre privação de sono e má postura ainda não
mereceu atenção. O presente estudo procurou avaliar a viabilidade da
hipótese dessa ligação e determinar o possível envolvimento de outros
fatores na relação. Métodos: Vinte médicos, dos quais 10 ortopedistas,
avaliaram o grau de risco de 23 posturas de alunos sentados expostas
em fotografias. Trinta e duas professoras experientes testemunharam
a ocorrência frequente das posturas ilustradas nas nove fotos que tiveram os maiores índices de risco. Resultados: Segundo elas, o hábito
(90%), a privação de sono (24%) e a preguiça (11%) são as causas das
más posturas. Entrevistas com 50 escolares de 8 a 14 anos, de ambos
os sexos, indicaram que uma parcela deles tem falta frequente de sono
e relatam dados adicionais que a comprovam. Trinta e nove (78%)
dentre 50 crianças relataram ter tido sonolência durante as aulas e
22 (44%) relataram ter já cochilado ao menos uma vez em sala de
aula. Sonolência e preguiça no dia seguinte à redução de sono foram
reconhecidas por 96% dos estudantes e 92% relatou sentar de modo
diferente nesses dias. Conclusão: Os dados obtidos sugerem garantir
a pertinência da hipótese de que a privação de sono pode ser correlacionada às posturas de risco constatadas em salas de aula e permitem
formular a hipótese de envolvimento da preguiça nessa relação.
Palavras-chave: privação do sono; postura; fases do sono; instituições acadêmicas; corpo humano; coluna vertebral/fisiologia; dor lombar/diagnóstico; nível de alerta/fisiologia; humano; criança.
INTRODUCTION
It is well-recognized that contemporary life imposes an excessive amount of demands on students and that their attendance
in classes reduces the amount of time necessary for sleep. When
human beings make up for lost sleep1, it seems to restore important homeostatic functions. Without this compensation,
mortality in humans2 or death in experimental animals3 may increase. In order to compensate for sleep deprivation, sleepiness
increases and subsequently causes all organisms to sleep. Sometimes, sleep occurs without regard to external conditions such
as when a truck driver is exhausted, falls asleep, and crashes4.
Nowadays, it is well-known that many children and adolescents have their sleep time significantly curtailed5. This is a
Study carried out at Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP), Botucatu (SP), Brazil.
1
Departamento de Pediatria, Faculdade de Medicina de Botucatu, Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP), Botucatu (SP), Brazil.
2
Departamento de Ciências Biológicas, Faculdade de Ciências, Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP), Botucatu (SP), Brazil.
Corresponding author: Luciana Marques Barros – Avenida Geraldo Roquete, 264 – Jardim Primavera – CEP 15600-000 – Fernandópolis (SP), Brazil – E-mail: [email protected]
Received: May 18, 2011; Accepted: July 25, 2011
Sleep Sci. 2011;4(3):�����
����
–92
Barros LM, Hoshino K
matter of concern because it promotes negative academic performance6. Indeed, sleepiness and even naps with bizarre seating postures are frequently seen in students during lessons,
indicating their need to compensate for sleep deprivation.
The manner in which the human body takes up space creates
different degrees of risk for the vertebral column7. Those having lower risks are considered correct postures, whereas higher
risk ones are categorized as inadequate postures8,9. Many inadequate postures exhibited in infancy may become habits and
evolve into vertebral column problems10 that eventually will
affect the quality of life11 and create high cost socio-economic
problems12. These concerns caused attention to be focused on
the bad postures frequently assumed by students seated in their
classrooms13. Attempts to eradicate such postures by substituting inappropriate-sized furniture by ergonomically-developed
tables and chairs caused negative results14,15. The persistence of
inadequate postures after furniture replacement indicates the
existence of one or more causal factors, among which sleepiness
may possibly be the most important.
The possibility that sleep deprivation increases or facilitates postures that may create problems in the vertebral column may be extended to other life conditions. Although
children, as cited before10, are more vulnerable to postural
risk factors, sleep deprivation and its causation of inadequate
postures may be observed also in adults, mainly in the sedentary activities of professionals. These facts make us ask
whether their effects on absenteeism and productivity are
caused by vertebral medical problems. This points out the
importance of the subject and validates future studies aiming to increase knowledge on the subject.
Notwithstanding the relevance of the relationship between insufficient sleep, inadequate postures in classroom
and development of future problems in the vertebral column,
the literature reveals no attention devoted to it. Such absence
of approach may be explained in different ways. Indeed, it
may result from the lack of opportunity to relate them. Another possibility is the risk to make a chimeric relationship
of independent phenomena. As known, two concomitant
manifestations displaying high correlation does not necessarily involve causal relationship. In order to discard such
possibility and disclose other involved factors, before higher
investment to test the causal relationship between sleep deprivation and bad posture, the present study sought to gather
information to grant the viability of the hypothesis. For this,
the study was carried-out in three distinct parts: the first
aimed to assess that different seating postures are displayed
by scholars in classrooms, and such postures are risk factors
for future development of problems in the vertebral column;
the second sought to confirm their spontaneous occurrence
in classrooms and collect opinions on their possible causes;
and the last one interviewed scholars to gather information
on their sleep habits, sleepiness and postures during lessons.
Preliminary approach on the possible relationships between
sleep and postures was also tried.
METHODS
General aspects and design
The present investigation was initiated after its approval
by the Ethics Committee of the Faculdade de Medicina de
Botucatu of Universidade Estadual Paulista, protocol number
011861,and obeyed all pertinent recommendations required
for research involving human subjects.
Diversity of postures in classrooms and their risk
One of present authors (LMB) frequented the State School
Cel. Francisco Arnaldo Silva, Fernandópolis (SP) fundamental teaching classes daily for 2 weeks, aiming to habituate
her presence and watch the bodily postures displayed by pupils during lessons. A sample of 120 standardized photos
of different seating postures was took in natural conditions
or reconstituted by demand. Twenty-three pictures (child
face occulted by a black strip) were selected after discarding
similar postures (based on the similarity of the head position
and vertebral column curvature). One picture displaying
correct posture was chosen and included in the sample. Selected pictures were numbered, printed and exhibited to 30
physicians, ten of whom were orthopedists. They were asked
to evaluate the risk of each posture for the development of
future problems in the vertebral column. This evaluation
was made scoring the risk in a scale ranging from 0 to 10,
with 0indicating absence of risk. Evaluations were made individually, in undisturbed personal offices, and without personal identification or time limitations.
Occurrence of high risk postures
The nine postures that received the highest means in risk
evaluation, plus the one that received the lowest one, were
presented to 32 experienced teachers (16.7±5.6 years teaching) asking them to select the postures they have detected
during their lessons. Opinions on the causative factor and
time of occurrence were also demanded.
Risk postures and sleepiness according scholars
Fifty scholars of both sexes, aged 8 to 14 years old (mean
10.08±1.67 years), from a school where bad posture pictures
were not took, were interviewed in order to evaluate their
sleep habits and perception on the sleepiness and risk postures
in classrooms. For this, a standardized sequence questionnaire
was used. One of us (LMB) was daily present in classrooms for
2 weeks and invited 4 or 5 children in the 3rd week to contribute for the search answering questions individually during
lesson intervals. Questions were made verbally and responses
Sleep Sci. 2011;4(3):�����
����
–92
89
90
Sleepiness and risk postures in classroom
recorded in the questionnaire. The questions made are ranked
in the Table 3. At the end, they were asked to evaluate whether
the postures depicted in a sample of 23 photos selected before
were determined by sleepiness or by laziness, and to report the
reasons for their judgments, because ill will emerged as one another possible causative factor of risk postures. The option to
not respond in cases of doubt was also allowed.
Data analysis
The obtained data was compiled in tables, and frequencies
and means (±standard deviation) were computed for the numerical descriptions only.
RESULTS
No posture evaluated by the physicians was considered free
of risk. The mean of evaluated risks ranged from the minimum of 1.95±1.36 until the maximum of 7.40±1.98. The
distribution of these means, presented according to classes of
risk level, is presented in Table 1. As depicted, the postures
displayed were evaluated as having median or high levels of
risk for future problems in the vertebral column.
Teacher’s data confirmed the spontaneous occurrence of
inadequate risk postures in classrooms. Table 2 depicts the
number of teachers who said they observed the postures displayed in each photo. The data show that no relationship exists
between the rate of risk and number of teachers that observed
these inadequate postures. Among 132 opinions given, 90 attributed risk postures as due to habit; 24 to sleepiness; and
11 to laziness. Furniture inadequate dimensions, tiredness,
careless, were the remaining opinions. Nine teachers reported
higher frequency of risk postures displays on Mondays and
Fridays, mainly in the first and last hours of the morning.
The interviewed students showed to sleep 8h28±0h41
daily, however, students studying in the morning period displayed 2h14 less sleep compared to those having lessons in
the afternoon, although they go to bed approximately at the
same hour (Table 3). Additionally to insufficient daily sleep
amount in many children, sleeping condition and problems
seem to contribute to somnolence occurrence in classrooms.
Forty-eight children reported that they awoke at night to
drink water or to go to the bathroom. Nine male students
said they were aware that they snored; one reported insomnia
and one was a somnambulist. Twenty-two children reported
that they sleep in noisy places, mainly with TV and traffic
related sounds. Sleeping alone in their bedroom (44%), with
one another person (38%), with two more persons (16%) or
with more than two persons (2%) was computed.
As shown in Table 3, the children stated that somnolence
and naps in classroom occur after nights with insufficientsleep and recognized that they became grumpy the day in
which they woke-up early or after a night they had gone to
Sleep Sci. 2011;4(3):�����
����
–92
bed late. The scholars reported also that, in the grumpy days,
they sat in different ways in class. A prevalent number of children stated that both laziness and sleepiness induced similar
postures, however some of them said sleepiness related postures are those with the greatest amount of head lean with
arms on the table or those with the head laying on the arms.
Table 1. Risk evaluation of postures displayed by scholars in classrooms.
Evaluation made by 20 physicians using a subjective scale ranging from 0
(without risk) to 10 (maximum risk). Postures exhibited in photos.
Risk level
Level limits
Evaluation frequencies
Very low
0.1-2.0
1
Low
2.1-4.0
0
Median
4.1-6.0
11
High
6.1-8.0
11
Very high
8.1-10.0
0
Table 2. Confirmation of risk posture manifestation by scholars seated in
classrooms. Percentage of teachers (n=32) that testified the occurrence of
postures depicted in nine pictures evaluated as having higher risk for the
vertebral column.
Risk
6.30 6.30 6.40 6.60 6.90 6.90 7.05 7.25 7.40
degree
%
44
16
28
28
56
59
13
53
28
Table 3. Sleep habits and related characteristics in scholars. Sleep parameters expressed in time and remaining data as absolute and percent
frequencies of the total number of scholars with morning or afternoon
lessons. Data computed from verbal information collected using a standardized sequence.
Morning students
(n=36)
Afternoon
students (n=14)
Mean hour to go bed
22h51±0h50
22h35±0h51
Mean awakening hour
6h18±0h30
8h32±1h10
Mean total sleep time
7h50±1h19
10h12±1h30
1 (3%)
9 (64%)
Awakening after many calls
30 (84%)
0 (0%)
Complaining great
sleepiness at waking
13 (36%)
1 (7%)
With sleepiness in
classroom
30 (83%)
9 (64%)
Took naps (at least once)
during lessons
10 (44%)
5 (36%)
Attributing sleepiness to
insufficient sleep
28 (78%)
9 (71%)
Reporting laziness after
insufficient sleep
34 (94%)
13 (93%)
Aware of postural
differences in lazy days
33 (92%)
13 (93%)
Sleep parameters
Sleep related information
Awakening spontaneously
Sleep, posture and laziness
Barros LM, Hoshino K
DISCUSSION
The data obtained in the present study indicates that students sitting in their classrooms display different bodily
postures and according to physicians’ evaluations, some of
these postures may be risk factors for the future development of problems in the vertebral column. The frequency
of these postures manifestation in class was confirmed by
teacher’s statements as being habitual. Finally, students reported that incorrect posture is related to insufficient sleep.
Jointly, these results indicate as pertinent the hypothesis
that sleep deprivation may be responsible for the incorrect postures maintained in classrooms and, by extension,
that this may be a risk factor for the future development of
problems in the vertebral column. This interpretation seems
valid because is in accordance with the concept that sleep
deprivation triggers many mechanisms to force the onset of
sleep and provides for the compensatory-rebound necessary
to restore homeostatic functions. In fact, sleeping bodies try
to turn themselves off by finding quiet places and increasing
sensory thresholds, developing photophobia, reducing mental activities such as awareness achieving relative immobility
and assuming specific postures, displaying decreased muscle
tone, reduced motor reflex speed, fatigue and a desire to remain immobile (seated or reclining)16,17. Sleepiness reduces
tolerance to prolonged muscular activities18 and bodily posture worsens in the initial 24 hours of sleep deprivation19,
reduces walking and produces a sensation of energy expenditure20. Under such conditions, sleepy children seem to try
different postures in classroom desks, maintaining for longer
periods, those that alleviate active muscular demand. It is
well-known that a behavioral pattern turns habitual when
its initial manifestations are followed by some consequence
(unconditioned stimulus or reinforcement). Many children
with chronic sleep debt repeat the inadequate postures and
seem to consolidate central mechanisms of postural organization that, in a subsequent step, may trigger them automatically even in the absence of sleepiness, turning habitual.
Silva21 and Tribastone22 call attention to such sequence of
events in the etiology of vertebral column problems.
The finding that laziness may be involved in the manifestation of inadequate postures was not foreseen in the present
study, but it seems pertinent and heuristically promising.
Laziness, indolence, sluggishness and slothfulness are synonymous and, although being a subject of interest in other
areas, has not been a subject of concern in health sciences.
Except for procrastination, which can be objectively defined
and understood23, no significant references can be found in
the literature. Notwithstanding this, the findings of the
present study lead us to consider that sleep deprivation effects look like laziness. Common sense defines laziness as a
state characterized by a lack of will and desire to engage in
activities (except those for age or acute survival demands,
like flirting, courtship, internet, eating etc.), procrastination, slackness, sleepiness and desire to remain relaxed seated or prone24. Similarly, after a brief period of excitement,
sleep deprivation increases somnolence in some activities
like eating and sexual activity24. Procrastination seems possible in sleep deprivation since sleepiness is the prevalent
motivational urge in such a condition. Hypotonic muscles24,
increases the sensation of energy expenditure20 and decreases
the tolerance for prolonged muscular activity18 which seems
to determine disinterest and reduced motor performance,
and creates the desire to stay seated or lie down. These similarities probably were considered by children when they reported insufficient sleep as responsible for both sleepiness
and laziness, which, in turn, determine inadequate seating
postures. The same causal agent (sleep deprivation) and the
same effect (inadequate posture) of both sleepiness and laziness strongly suggest that they are the same entity. In other
words, laziness may be a denomination of the organism state
comprising the entire set of sleep deprivation effects.
Laziness and sleep deprivation may be alternatively
thought of as distinct phenomena, with different roles, but
sharing some common manifestations. Distinctive causes
and/or effects may support this possibility. The head positioning reported by students as showing a difference between sleepiness and laziness, as an example of inadequate
posture seems to be much more of an intensity determined
factor than one of independent origin. Laziness can be frequently manifested without detectable sleep curtailment.
Its proverbial increase in adolescence is considered as a normal manifestation determined by natural development24.
Recent findings, however, indicate that sleep deprivation
is common in adolescents due to the normal delay in melatonin (a sleep facilitating hormone) secretion associated
with early awakening forced by academic demands25. On
the other hand, there are many sleep disorders and conditions that affect sleep without common noticeable cues.
They induce laziness that is perceived as being spontaneous. The third alternative to explain the similarities between laziness and the effects of sleep deprivation may consider laziness as only a part of sleep deprivation induced
effects. Such a possibility does not hold up because, beyond
effects and manifestation similarities, their ultimate functional roles converge to save energy.
Finally, it is possible that laziness could help a student
to sleep. This appears to be the major contribution of this
study. This hypothesis seems to support one obvious fact
that leads one to ask why it has not been considered before.
The reason seems to be most likely due to the moral and religious connotations given to laziness24. In fact, in all human
history, laziness was conceived as a sin or as a personal moral
Sleep Sci. 2011;4(3):�����
����
–92
91
92
Sleepiness and risk postures in classroom
character defect which was not the purview of the health sciences. Considering laziness as an adaptive process that in the
end can provide homeostatic restoration makes the subject
emerge into the biomedical area requiring many new studies. Such efforts to increase knowledge on the subject will
surely be appreciated because they may decrease fighting
and suffering promoted by the misconception that laziness
is morally undesirable. In the same way, bad posture in a
classroom is not necessarily a sign of carelessness.
References
1. Dement W. The effect of dream deprivation. Science.1960;131:
1705-17.
2. Grander MA, Hale L, Moore M, Patel NP. Mortality associated
with short sleep duration: the evidence, the possible mechanisms,
and the future. Sleep Med Rev. 2010;14(3):191-203.
3. Rechtschaffen A, Bergmann BM, Everson CA, Kushida CA, Gilliland MA. Sleep deprivation in the rat: X. Integration and discussion of the findings. Sleep. 2002;25(1):68-87.
4. Mello MT, Santos EHR, Pires MLN. Sonolência e acidentes. In
Tufik S, editor. Medicina e biologia do sono. Barueri: Manole;
2008. p.416-20.
5. Andrade MMM. Padrões temporais das expressões da sonolência em adolescentes. [tese]. São Paulo: Universidade de São
Paulo; 1997.
6. 6.Gruber R, Wiebe SS, Wells SA, Cassoff J, Monson E. Sleep and
academic success: mechanisms, empirical evidence, and interventional strategies. Adolesc Med State Art Rev. 2010;21(3):522-41.
7. Magee DJ. Avaliação músculo-esquelética. São Paulo: Manole;
2002.
8. Silva OL. Semiologia do aparelho locomotor. Rio de Janeiro:
Guanabara-Koogan; 2003.
9. Adams MA, Hutton WC. The effect of posture on the lumbar
spine. J Bone Joint Surg. 1985;67(4):625-9.
10.Souchard PE. Ginástica postural global. 2a. ed. São Paulo: Martins Fontes; 2003.
11.Kendall FP, McCreary EK, Provance PG. Músculos, provas e funções. 4a. ed. São Paulo: Manole; 1995.
Sleep Sci. 2011;4(3):�����
����
–92
12.Kirkpatrick JS. Oh, my aching back: evaluation and surgical treatment of lumbar spine disorders. South Med J.
1996;89(10):935-9.
13.Oliver J. Cuidados com a coluna. São Paulo: Manole; 1999.
14.Ferriani MG, Cano MA, Candido GT, Kanchina AS. Levantamento epidemiológico dos escolares portadores de escoliose da rede pública de ensino de 1º grau no município de Ribeirão Preto. Rev Eletr Enferm [Internet]. 2002 [citado 2004
20 Jan]2(1) Disponível em: <http://www.fen.ufg.br/revista/
revista2_1/28.05.2008/Levanta.html>.
15.Rosa GM, Gaban GA, Pinto LD. Adaptações morfofuncionais do
músculo esquelético relacionados à postura e o exercício físico.
Rev Fisioter Bras. 2002;3:100-5.
16.Kleitman N. Sleep and wakefulness. Chicago: The University of
Chicago Press; 1963.
18.Andersen ML, Bittencourt LRA. Fisiologia do sono. In: Tufik S,
editor. Medicina e biologia do sono. Barueri (SP): Manole; 2008.
p.48-58.
19.Nakano T, ArakakiK, Michimori A, Inbe H, Hagiwara H, Koyama E. Nineteen-hour variation of posturals way alertness and rectal temperature during sleep-deprivation. Psychiatry Clin Neurosci. 2001;55(3):277-8.
20.Griebble M, Hertel J. Changes in postural control during 48-h,
sleep deprivation period. Percept Mot Skills. 2004;99(3 Pt
1):1035-45.
21.Martin BJ. Effect of sleep deprivation on tolerance of prolonged
exercise. J Appl Physiol Occup Physiol. 1981;47(4):345-54.
22.Silva OL. Semiologia do aparelho locomotor. Rio de Janeiro:
Guanabara Koogan; 2003.
23.Tribastone T. Tratado de exercícios corretivos aplicados à reeducação motora postural. São Paulo: Manole; 2001.
24.Kerbauy RR. Procrastinação: adiamento de tarefas. In: Banaco
RA, organizador. Sobre comportamento e cognição. São Paulo;
AR Bytes Editora; 2001. v. 2. p.435-40.
25.Valentim MG. Preguiça: um problema da adolescência negligenciada pela pesquisa? [tese]. Botucatu: Universidade Estadual Paulista; 2006.
26.Carskadon MA, Acebo C, Jenni OG. Regulation of adolescent
sleep: implications and behavior. Ann N Y Ac Sci.2004;1021:27691. Comment in: Ann N Y Acad Sci. 2004;1021:292-3.