Sleep, 3(3/4):221-224
© 1980 Raven Press, New York
Some Epidemiological Data on Snoring and
Cardiocirculatory Disturbances
E. Lugaresi, F. Cirignotta, G. Coccagna, and C. Piana
Institute of Clinical Neurology, University of Bologna, Italy
Our previous studies indicated that heavy and habitual snoring may adversely
influence cardiac and circulatory function (Lugaresi et aI., 1975, 1978). To test
whether heavy and habitual snoring is a predisposing factor in patients with
hypertension and cardiocirculatory disease in general, we have started an epidemiological survey on snoring.
METHODS
The survey was carried out in the territory of the Republic of San Marino,
which is an independent state inhabited by 20,000 people and is located in the
southern part of the Emilia-Romagna region (northeastern Italy), All the citizens
of this independent state can take advantage of their free national health service,
which provides periodical clinical and laboratory checkups, which are recorded in
individual personal medical files. Questionnaires on all the sleep disorders were
collected over a period of 3 years by one investigator. The ideal weight for each
individual was calculated following the formula of Lorenz as modified by Vague et
ai. (1974).
RESULTS
Ii,)
A total of 5,713 individuals was examined; 16.8% of males and 14.1% offemales
stated that they snored occasionally, while 59,1% of the males and 72.1% of the
females stated that they did not snore or were not aware of it. Finally, 19% of the
population were habitual snorers; this corresponds to 24.1% of the male and
13.8% of the female population.
The frequency of snorers increased with age. Up to 30 years of age, approximately 10% of males and less than 5% of females were habitual snorers. In the
population over 30 years of age, these percentages increased more rapidly among
males than among females. Between 60 and 65 years of age, more than 60% of
males and about 40% of females were habitual snorers (Fig. 1).
The occurrence of systemic hypertension (defined as a maximum systolic pressure greater than 160 mm Hg) was also considered, The population was subdivided into three different age groups (21-40, 41-60, and 61-80 years old). As
Accepted for publication September 1980.
Address correspondence and reprint requests to Dr. Lugaresi at Clinica Neurologica dell'Universita
di Bologna, Via U. Foscolo 7, 40123 Bologna, Italy.
221
E. LUGARESI ET AL.
222
%
,00
90
80
70
60
CJ_
ff :~:}}}
95 I CONFIDENCE
LIMITS
50
40
30
20
10
o
5 1b
1'5
20
25
30
3'5 4'0 4'5
50 55 60 6'5 io i5 80
85 yrs
..
FIG. 1. Prevalence of habitual snoring in the population sample examined, distributed according to
age and sex.
expected the frequency of hypertension increased with age: hypertension was present in 2.S% of the individuals betweeen 21 and 40 years of age, in 10.4% between
41 and 60, and 27.6% between 61 and SO.
,
The occurrence of hypertension in the same population subdivided into
nonsnorers and habitual snorers was also analyzed. In each age group, hypertension was more .frequent among habitual snorers than among nonsnorers. This
difference was particularly significant after age 40 (especially in the 41-60 group)
(Fig. 2).
Because the higher incidence of hypertension among snorers could be due to the
concomitant high incidence of obesity among snorers, we analyzed the correlations of hypertension, obesity, and snoring. After further subdividing our po pula-
%
:r = 95% CONFIDENCE
40
~
NON SNORERS
fZ'Zm
29.9%
H. SNORERS
30
20
10
0
LIMITS
20.6 %
15.2 %
7.5 %
2.5 %
cb
3.4%
~
21 - 40
~
41 - 80
0
61-80,r5
FIG. 2. Prevalence of hypertension among habitual snorers and nonsnorers, subdivided into three age
groups.
Sleep. Vol. 3, No. 3/4. 1980
'.
SNORING AND CARDIOVASCULAR DISTURBANCES
D
NON
SNORERS
_
HABITUAL
223
SNORERS
WEIGHT
21.4%
0"
21.4%
22.0%
15' INCREASE
AND
26.6%
OVER
I=95'1. CONFIDENCE
LIMITS
%
27.6%
BELOW
15% INCREASE
16.8%
FIG. 3. Prevalence of hypertension between 41 and 80 years of age among habitual snorers and
nonsnorers. subdivided into overweight individuals (weight greater than 15% of ideal) and normalweight individuals (weight not more than 15% of ideal).
>.
tion into overweight individuals (characterized by a weight higher than 15% of the
ideal weight) and normal-weight individuals (weight not greater than 15% of the
ideal), we found that 54% of the overweight subjects were habitual snorers,
whereas only 34% of the normal-weight subjects were. Similarly, 22% of the
overweight subjects were hypertensive compared to 13% in the normal-weight
group. From these data, one could hypothesize that obesity is the primary factor
responsible for snoring and hypertension. However, this was not supported by a
further analysis in which hypertensive snorers and nonsnorers were compared,
with weight as the independent variable. In the overweight group there was no
significant difference between snorers and nonsnorers in arterial pressure. However, there was a highly significant difference in arterial pressure between snorers
and nonsnorers in the normal-weight group among both men and women (Fig. 3).
Finally, our questionnaire included a question regarding cardiac disturbances:
limiting our analysis to nonobese individuals (weight not greater than 30% of the
idea!), we found that both male and female habitual snorers complained more
often than non snorers of symptoms of cardiac dysfunction (Fig. 4).
DISCUSSION
Our epidemiological data show that snoring is a frequent phenomenon. It is
prevalent among males and becomes habitual earlier in men than in women. There
may be a number of explanations for the correlation between snoring and hypertension. One hypothesis is that both are the consequence of an unknown factor.
However, our previously published polygraphic data have shown that snoring
impairs circulatory function (Lugaresi et al., 1975" 1978). These preliminary epi-
',I
Sleep, Vol. 3, No. 3/4, 1980
'.
E. LUGARESI ET AL.
224
I = 95% CONF IDENC E
%
rY"
50
WEIGHT
LIMITS
9
42.3%
40
BELOW 30% INCREASE
30
20
10
0
20.3%
15·1%
11.2%
d:J
c:::J NON
SNORERS
D
~H.SNORERS
FIG. 4. Prevalence of cardiac disturbances among habitual snorers and nonsnorers 41-80 years of age,
having a weight not more than 30% of the ideal weight.
demiological data therefore suggest that heavy and habitual snoring represents a
risk factor for the cardiovascular system.
REFERENCES
Lugaresi E, Coccagna G, Fameti P, Mantovani M, and Cirignotta F. Snoring. Electroencephalogr Clin
Neurophysiol 39:59-64, 1975.
Lugaresi E, Coccagna G, and Cirignotta F. Snoring and its clinical implications. In: C G\!illeminault
and WC Dement (Eds), Sleep Apnea Syndromes. Alan Liss, New York, 1978, pp 13-21.
Vague J, Rubin P, JUbelin J, Lam-Van G, Wasserman AM, and Fondarai J. Regulation of adipose
mass: Histometrical and anthropometrical aspects. In: J Vague (Ed), The Regulation of the Adipose
Tissue Mass, Excerpta Medica, Amsterdam, 1974, pp 296-310.
Discussion
Dr. Phillipson asked what was the mechanism that caused sustained systemic and pulmonary arterial hypertension, He understood why there are cyclic increases in arterial
pressures during the obstruction, but this did not explain the elevated daytime levels.
Dr. Lugaresi replied that it was clear that the Mueller maneuver (inspiratory effort
against a closed upper airway) was an important cause of the acute changes, but he did not
know the explanation of the sustained increased.
Dr, Sutton suggested that sodium retention throughout the night might be a factor in
causing the sustained hypertension. He noted that acromegalic patients usually had systemic hypertension and that sodium retention was part of the mechanism.
Dr. Lugaresi asked all those who study patients if they had seen hypersomnia in patients
with central apnea or hypo ventilation. He did not think that this symptom occurs in such
•
patients.
Dr. Guilleminault quoted the Stanford group, which had found 26 patients with central
apnea; daytime hypersomnolence did occur in these patients and was correlated with the
number of apneas.
Dr. Weitzman said that they had studied 2 patients who developed central apnea many
years after bulbar poliomyelitis; their major symptom was increasing somnolence, which
improved after therapy.
Sleep, Vol. 3, No. 314,1980
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