The effect of seasonal variation on sexual behaviors in males and its correlation with hormone levels: A prospective clinical trial

Abstract

Introduction
We examined the effect of seasonal variation on sexual behavior and its relationship with testosterone levels. The existence of the inhibiting effect of cold stress on sexual behavior and testosterone levels was our hypothesis.

Material and methods
A total of 80 cases, aged between 20 and 35 years old, were enrolled. Blood samples for testosterone, FSH, LH, and prolactin were obtained twice from each participant at the same time of day (before 10 am). The first samples were taken in January and February, the months which have the average lowest heat days (-15.9°C and -14.6°C, respectively) in our region. The second samples were taken in July and August, which has the average highest heat days (25.4°C and 26.1°C, respectively) in our region. Two times IIEFs (International Index of Erectil Function) were fulfilled at the same day of taking blood samples. The frequency of sexual thoughts and ejaculation were questioned by asking “How many times did you imagine having sex?’’ and “How many times did you ejaculate in a week?”. The body mass index of the participants in the study was calculated in the winter and in the summer.

Results
There were significant differences in terms of IIEF scores, frequency of sexual thoughts and ejaculations, BMI (Body mass index), and both testosterone and FSH levels between the winter and summer measurements. We did not find any significant differences with regards to prolactin and LH levels.

Conclusions
Although testosterone levels are within normal limits in both seasons, its level in cold months is less than in hot months. Testosterone levels can change according to the season. The impact of cold seasons in particular should be taken into account when evaluating testosterone levels and sexual status, as well as the other influences (social, cultural).

Full text

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Central European Journal of Urology
O R I G I N A L P A P E R
ANDROLOGY
The eect of seasonal variaon on sexual behaviors
in males and its correlaon with hormone levels:
a prospecve clinical trial
Aslan Demir, Mehmet Uslu, Omer Erkam Arslan
Kaas University, Medical School, Department of Urology, Kars, Turkey
Key Words: seasonal variaon ‹› cold stress ‹› sexual behavior ‹› testosterone
Cent European J Urol. 2016; 69: 285-289 doi: 10.5173/ceju.2016.793
INTRODUCTION
Sex is a fundamental part of the human life that
is expressed in countless ways of varying depth and
complexity. The reality that men and women think
about one another as potential partners, irt, tell sa-
lacious jokes, and sometimes even end up having sex
is the basis for television shows, movies, books, and
everyday ofce gossip [1]. Does frequency of such be-
havior change seasonally?
According to a special report by Lauritsen et al.
regarding seasonal patterns in criminal victimiza-
tion trends, adult rates of simple assault exhibited
relatively less seasonal uctuation but were highest
in the summer [2]. Can testosterone be a culprit in
such crimes?
Numerous experimental and clinical studies have
investigated stress factors such as immobilization,
heat, light, electrical foot shocks, cold, ether, exer-
cise, and food restriction that cause males to expe-
rience anxiety about their sexual behavior [3, 4].
There may be many factors that regulate male sexu-
al behavior, as well as the psychological mood. Males
under stress may exhibit suppression of testosterone
Citaon: Demir A, Uslu M, Arslan OE. The eect of seasonal variaon on sexual behaviors in males and its correlaon with hormone levels: a prospecve
clinical trial. Cent European J Urol. 2016; 69: 285-289.
Arcle history
Submied: Feb. 1, 2016
Accepted: May 9, 2016
Published online: Aug. 22,
2016
Introducon We examined the eect of seasonal variaon on sexual behavior and its relaonship with
testosterone levels. The existence of the inhibing eect of cold stress on sexual behavior and testoster-
one levels was our hypothesis.
Material and methods A total of 80 cases, aged between 20 and 35 years old, were enrolled. Blood
samples for testosterone, FSH, LH, and prolacn were obtained twice from each parcipant at the same
me of day (before 10 am). The rst samples were taken in January and February, the months which have
the average lowest heat days (-15.9°C and -14.6°C, respecvely) in our region. The second samples were
taken in July and August, which has the average highest heat days (25.4°C and 26.1°C, respecvely) in our
region. Two mes IIEFs (Internaonal Index of Erecl Funcon) were fullled at the same day of taking
blood samples. The frequency of sexual thoughts and ejaculaon were quesoned by asking “How many
mes did you imagine having sex?’’ and “How many mes did you ejaculate in a week?”. The body mass
index of the parcipants in the study was calculated in the winter and in the summer.
Results There were signicant dierences in terms of IIEF scores, frequency of sexual thoughts and ejac-
ulaons, BMI (Body mass index), and both testosterone and FSH levels between the winter and summer
measurements. We did not nd any signicant dierences with regards to prolacn and LH levels.
Conclusions Although testosterone levels are within normal limits in both seasons, its level in cold
months is less than in hot months. Testosterone levels can change according to the season. The impact
of cold seasons in parcular should be taken into account when evaluang testosterone levels and
sexual status, as well as the other inuences (social, cultural).
Corresponding author
Aslan Demir
Kaas University Medical
School
Department of Urology
Center of the city
36100 Kars, Turkey
phone: +90 532 465 82 25
benaslandemir@yahoo.
com.tr

Central European Journal of Urology
286
cal examination such as varicocele or atrophic testis
were excluded from the study.
Blood samples were obtained twice from each par-
ticipant at the same time of day (before 10 am).
The rst samples were taken at the end of February.
The second samples were taken at the end of August.
International Index of Erectile Function (IIEF) forms
were fullled at the same day of taking blood sample
twice over the course of the study. The frequency
of sexual thoughts and ejaculation were questioned
by asking on a special form “How many times did
you imagine having sex?’’ and “How many times did
you ejaculate in a week, except ejaculations produced
by nocturnal imagination?”. The body mass index
of the participants in the study was calculated at the
same day of taking blood sample.
Stascal analysis
This study was designed to detect a 30% difference
in hormone levels between the groups with 90%
power, assuming a signicance level of 0.05 using
two-tailed statistical tests. Sample size was calcu-
lated based on the results of a pilot study of hor-
mone levels in consultation with a biostatistics spe-
cialist. Results are presented as mean ± standard
deviation. Data were analyzed using SPSS 16.0
for Windows (SPSS, Inc., Chicago, IL, USA). Dif-
ferences between the results in terms of hormones,
body mass indices (BMI), IIEF scores, and frequen-
cy of sexual thoughts were analyzed using paired-
samples student t tests.
RESULTS
The mean age of the patients was 27.8 years
(min: 20, max: 35). There were signicant dif-
ferences in terms of IIEF scores (24.05 ±2.1 and
24.5 ±1.7, p = 0.006), frequency of sexual thoughts
(17.4 ±11.04 and 28.1 ±14.1, p = 0.001) and ejac-
ulations (2.31 ±1.15 and 7.16 ±2.49, p = 0.001),
BMI (25.7 ±6.1 and 26.16 ±8.15 kg/m2, p = 0.002)
and both testosterone (360.2 ±107.4 and 524.2
±130.01 ng/dL, p = 0.001) and FSH levels (3.77 ±2.47
and 4.3 ±2.8 mIU/ml, p = 0.03) (Table 1, Figure 1)
between the winter and summer measurements.
We did not nd any signicant differences with re-
gards to prolactin and LH levels (Table 1).
DISCUSSION
Ample evidence exists to support the concept of di-
urnal changes in testosterone levels, but, substan-
tiations for seasonal uctuations is rare and incon-
sistent. Since circadian disparities exist, the blood
secretion, spermatogenesis, and libido [3]. Cold has
been regarded as a stress factor in many experi-
mental studies [3, 5]. Cold stress has been dened
as acute and chronic cold stress in terms of exposure
time, according to animal studies [5]. It is dened
as expose to the cold at +4°C for 8 hours for only
once and +4°C for 4 hours daily for at least 21 days,
for acute and chronic cold stress, respectively [5].
Our region is one of the coldest areas in eastern Tur-
key. The average lowest temperatures for January
and February are -15.9°C and -14.6°C, respectively.
The average highest temperatures in July and Au-
gust are 25.4°C and 26.1°C, respectively according
to the data from Turkey Meteorology Institute.
In this study, we examined the seasonal variation
on sexual behavior and its relationship with testos-
terone levels. The existence of the inhibiting effect
of cold stress on sexual behavior and testosterone
levels was our hypothesis.
MATERIAL AND METHODS
The study was designed as a non-randomized pro-
spective trial. Permission for the study was obtained
from the Regional Ethics Committee and performed
in accordance with the World Medical Association’s
Helsinki Declaration (Ethics Committee approval
number: 80576354-050-99/01). Informed consent
was received from all cases.
A total of 80 cases living in Kars over one year, aged
between 20 and 35 years old, were enrolled into the
study. All cases in this study were married. The par-
ticipants were in particular chosen from the ones
who work outdoors in their work place or who are
exposed to the cold for at least one hour, for instance
walking in the morning and evening hours to their
work place and home in their normal winter clothes.
Our participants were exposed to the cold for
at least 60 days (the two coldest months in our re-
gion) at -15.9°C and -14.6°C, respectively, which was
slightly different from the chronic cold stress deni-
tion in terms of exposure time and coldness degree.
Blood samples were obtained from the participants
at the end of February.
Exclusion criterias
The cases with erectile dysfunction (psychogenic
or organic etiology), who are single, those in whom
the ejaculations were produced by nocturnal imagi-
nation, psychological problems, drug-using history,
or libido failure, those with a low hormone prole
in terms of testosterone, prolactin, follicle-stimulat-
ing hormone (FSH), or luteinizing hormone (LH),
and the cases who have any abnormal genital physi-

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Central European Journal of Urology
Testosterone has been shown to follow a seasonal
variation in many species, especially in males, that
can promote changes in human behavior and physi-
ology, such as waist-to-hip ratio, relationship sta-
tus, and sexual intercourse [8]. While the majority
of studies report that testosterone concentrations
peak in the fall for men, other have reported peaks
during other months of the year. Inconsistencies
in prior ndings may have resulted from the var-
ied nature of different studies; some used atypi-
cal populations, used participants of only one sex,
or collected samples over less than a full year.
For that reason, the nature of the seasonal variation
in humans’ testosterone concentrations remains
poorly characterized [8].
Cold is an interesting and poorly investigated fac-
tor that may signicantly affect human physiology.
A study showed that in tropical men who were accli-
matized to Antarctica cold, exposure to cold for vari-
ous durations caused increased excretion of urinary
epinephrine, norepinephrine, and salivary cortisol
levels associated with signicant autonomic changes
in heart rate and blood pressure [5]. So, in this work,
we aimed to understand the cold effect in terms
of seasonal variations on the hormone prole, in-
cluding testosterone, LH, FSH, and prolactin and
sexual behaviors.
The hypothalamic-pituitary-gonadal (HPG) axis
has a critical role for the development and adult-
hood in four physiological processes: 1) phenotypic
gender development during embryogenesis, 2) sex-
ual maturation at puberty, 3) testis endocrine func-
tion- testosterone production, and 4) testis exocrine
function-sperm production [9]. Androgen affects
the growth and development of the male repro-
ductive system and secondary sex characteristics,
as well as the libido and sexual behavior [9].
According to the Mulligan and Schmitt’s study, tes-
tosterone enhances sexual interest and increases
the frequency of sexual acts and nocturnal erec-
tion, but has little or no effect on fantasy – induced
or visually – stimulated erections [10]. The most
important hypothalamic hormone for androgen
production is gonadotropin-releasing or luteiniz-
ing hormone-releasing hormone (GnRH or LHRH).
GnRH secretion results from an integrated input
from the effects of stress, exercise, and diet from
higher brain centers [9]. The stress response
to physical or psychological stressors can affect
the HPG axis by inhibiting it [4].
The magnitude of the stress depends on the type
and duration of the stressor [11]. According to the
model in several studies, acute stress exposure can
change from seconds to a few hours, and chronic
stress exposure usually lasts at least 20 days [3].
samples have traditionally been obtained in order
to know the testosterone levels in the early morning.
Current research suggests that while some evidence
exists to support the notion of seasonal testosterone
changes, the discussed inconsistencies preclude the
incorporation of this concept into current clinical
standards [6].
Moskovic et al. investigated seasonal uctuations
in some hormones, including testosterone, in men
by month and by season. According to their results,
no differences in testosterone or free testosterone
were established. Statistically signicant evidence
of changes in estradiol and testosterone/estrogen
ratio were identied in men included in their study.
According to their comments, although this is con-
sistent with seasonal body habitus changes, physical
activity levels, and hypothesized hormonal patterns,
the variability reported in the literature makes fur-
ther trials covering a broader geographic region im-
portant to conrm the ndings [7].
Table 1. The results with the standard deviaons of study,
signicance p <0.05
n=80
In winter In summer p
Parameters
IIEF scores 24.05 ±2.1 24.5 ±1.7 0.006
Frequency/ week 17.4 ±11.04 28.1 ±14.1 0.001
Ejaculaon/week 2.31 ±1.15 7.16 ±2.49 0.001
BMI (kg/m2) 25.7 ±6.1 26.1 6 ±8.15 0.002
Testosterone (ng/dL) 360.2 ±107.4 524.2 ±130.01 0.001
FSH (mIU/ml) 3.77 ±2.47 4.3 ±2.8 0.03
LH (mIU/ml) 4.75 ±1.83 4.77 ±1.53 0.93
Prolacne (ng/ml) 7.95 ±3.6 11.2 ±4.2 0.25
Figure 1. Testosterone levels according to the season, *p <0.05.
Testosterone: ng/dL (218–906 ng/dL).

Central European Journal of Urology
288
as low levels of plasma testosterone both in breed-
ing and hibernating seasons. There was no signi-
cant difference in terms of results after seven days
of cold exposure [15].
According to our results, although the values
of testosterone and FSH in winter and summer fell
within normal limits, the difference between these
parameters was signicant statistically (Table 1).
There was not any statistical difference in terms
of the LH values in winter and summer. “Perhaps
for that reason, the values of testosterone were
within normal limits in both seasons”. According to
some studies, male sexual activity increased plasma
levels of both corticosterone and testosterone. This
nding has been established in rats, mice, tritons,
amphibians, and lizards. However, the physiological
mechanism of this effect is still unknown [3]. Fur-
thermore, sexual behavior and mating have bene-
cial effects on neuronal and endocrine responsive-
ness to stress and have an anxiolytic-like effect
[16, 17]. “Namely, the sexual activity in males oper-
ates as a protective effect against the cold environ-
ment as a rationalization or defensive mechanism
of nature”.
Our results revealed a statistical difference
in terms of BMI results (Table 1). This result
is consistent with the Retana-Marquez’s et al.
study [4]. In our opinion, the mechanism of the
difference with regard to BMI is associated with
the suppression of appetite and feeding behavior
in stressful conditions, for instance during expo-
sure to the cold in winter. The summer may affect
the appetite and feeding behavior positively. The
summer diet may also affect the hormone levels
and sexual behaviors. However, in contrast, there
may be the effect of the hormones on metabolism
such as testosterone with the different pathways.
But, we believe that further randomized prospec-
tive controlled studies are needed to explain these
questions and pathways.
Limitaons of study
One of the limitations of our study was the lack
of an acute group (exposing to the cold once but
for a long time, about 8 hours). Another was that
it was carried out in a single center. The third is the
age range, in which a greater range until 60 years
old was not included; it could obtain the comparative
results in terms of the ages. Also, the summer dates
chosen are usually associated with summer holidays,
a fact that could inuence sex behaviors (more free
time, etc.) and hormones (sleeping time, outdoor
activities, etc). Thus, these observations can affect
our results.
According to these models, our study is acceptable
as a chronic stress exposure because of the expo-
sure time that was about 60 days at -15.9°C and
-14.6°C degrees. In some studies, while acute stress
did not modify testosterone, decrease plasma LH
and testosterone, or increase testosterone in ham-
sters and humans, it decreased serum levels of LH
and testosterone in rabbits, macaques, and ba-
boons [3]. Rekkas et al. established that testoster-
one in the blood of three breeds of rams showed
a seasonal variation [12]. Namely, the responses
to the same stress effect can change from species
to species. On the other hand, chronic stress in rats,
hamsters, and men has been known to have an in-
hibitory effect on the HPG axis through decreasing
LH and testosterone [3].
It is well known that masculine sexual behavior
depends mainly on testosterone, whose secretion
is suppressed by stress [4, 13]. While many kinds
of acute stress have been studied, chronic ones have
been rarely studied. Moreover, responses to the
kind of stressors changed from species to species.
This situation can be explained as a rationaliza-
tion or defensive mechanism for survival in the face
of stressors that the test subjects have exposed
themselves. For instance, in Talapoin monkeys,
subordinate males (undergoing social stress) dis-
play neither an increase in aggression nor sexual
behavior, as independent from their plasma LH
and testosterone levels [3]. For this reason, the
main purpose of our study was to identify the effect
of chronic cold stress on male sexual behavior and
on testosterone, FSH, LH, and prolactin levels.
According to the ndings of Retana-Marquez et al.,
sexual behavior in male rats depends on the char-
acteristics of each stressor and on the duration
of exposure (either acute or chronic). According
to their results of the immersion cold water stress-
or, low body temperature could be partially respon-
sible for the low performance in sexual behavior
[3]. According to our results, the frequency of the
sexual thoughts and weekly ejaculations decreased
in winter (Table 1). Panesar et al. showed that low
temperatures slowed down metabolism, partly be-
cause the kinetic energy of molecules was reduced
and enzymes might be structurally impaired.
As a result, testosterone production was completely
impaired [14]. In addition to these studies, Parua
et al. investigated the effect of cold stress on plasma
testosterone levels in toads (Bufo melanostictus)
during breeding and hibernating seasons for peri-
ods of 7, 14, and 21 days. Their results revealed that
cold-exposed animals displayed a decrease in testic-
ular weight, testicular delta 5–3 beta, and 17 beta-
hydroxysteroid dehydrogenase activities, as well

289
Central European Journal of Urology
in particular should be taken into account when
evaluating testosterone levels and sexual status,
as well as the other inuences (social, cultural).
CONFLICTS OF INTEREST
The authors declare no conicts of interest.
CONCLUSIONS
Although testosterone levels are within normal lim-
its in both seasons, its level in cold months is lower
than the hot months. Testosterone levels can change
according to the season. The impact of cold seasons
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