The Effect of Eating Habits on Sleep Quality in 19-24 Years Old Young Adult Women

The transition period to university is one of the critical stages in terms of gaining weight and fat since it also covers the adolescence period [1,2]. The students in this period are at risk in relation to nutrition and health [3]. This is due to some nutritional changes during this stage as a result of leaving the family, changing the settlement, and starting an independent life [4,5]. Most university students cannot afford the recommended dietary intake, and this results in unwanted weight gains [2,6]. The weight gain and changing eating habits during this period might lead to undesirable consequences in the later stages of life in terms of the development of certain diet related chronic diseases (obesity, cardiovascular diseases and type 2 diabetes) [7]. Increasing metabolic diseases and obesity prevalence cause significant reduction in sleep duration [8]. Sleep is a vital part of health affecting the life quality and wellbeing of individuals [9]. Most adults need 7-8 hours of sleep a day [8]. However, need for sleep may show variability depending on such individual and environmental factors as age, gender, physical activity, history of disease, emotional state, and lifestyle [10]. Sleep affects eating times as well as eating structure [11]. In addition, duration and quality of sleep is among the causes responsible for food consumption and weight gain. In a recent study, it has been determined that sleep duration is also affected by food consumption [12] and stated that a healthy diet could correct sleep deprivation [8]. One of the reasons for the increase in food consumption is inadequate or excessive sleep duration. Both of these conditions can adversely affect sleep quality [13]. Additionally, it has been stated that poor sleep quality might lead to weight gain, obesity, diabetes, cardiovascular diseases, physical diseases and decreased performance [14]. The relationship between decreased sleep duration and weight gain can be explained by a decrease in leptin hormone level activating the satiety signal and an increase in appetite-stimulating ghrelin hormone levels as a result of decreased sleep duration [13]. Some studies have indicated a significant relationship between both short and long sleep duration Crimson Publishers Wings to the Research Research Article


IOD.000572. 3(5).2020
and body mass index (BMI) [15,16]. Sleeping less than six hours has an impact on obesity development by resulting in more adipose tissue development and weight gain [8,17]. Consuming energy rich food (high fat or refined carbohydrate-containing foods), skipping meals, and consuming inadequate vegetables may lead to less sleep duration [8]. It has been found in a study conducted in Japan that individuals who eat high fat, skip breakfast, eat mainly fast food, and usually eat out have shorter sleep durations [18]. Unfavorable conditions stemming from school exams, course schedules, and social circles in hostels and dorms may cause university students to experience sleep problems. Many recent studies have shown that eating habits have an effect on sleep durations. However, there are few studies in Turkey investigating the relationship between eating habits and sleep quality. For this reason, this study aims to investigate the effect of eating habits on sleep quality in young adult women aged between 19 and 24.

Materials and Methods
This study was carried out on 412 female university students aged between 19 and 24 staying in dormitories in Ankara province between December 2015 and May 2016. The Helsinki Declaration principles were followed in the study. The students were informed about the purpose of the study, and those who volunteered to participate were involved in the study. The data of the study were collected through face-to-face interviews using questionnaires prepared by the researchers. The questionnaire form consisted of general information about students, their height, body weight, eating habits, and the Pittsburg Sleep Quality Index (PSQI). The body weight (kg) and height (cm) measurements of the individuals were collected by the researches in accordance with general practices. Body Mass Index (BMI: kg/m 2 ) was calculated for all individuals. According to the World Health Organization (WHO), BMI is classified as "thin" for less than 18.5kg/m 2 , "normal" for 18.5-24.9kg/m 2 , "overweight" for 25.0-29.9kg/m 2 , and "obese" for ≥30kg/m 2 . Later, 25.0-29.9kg/m 2 and ≥30 kg/m 2 categories were combined to make a single category as "pre-obese/obese" for ≥25kg/m 2 [19].
PSQI was used for the evaluation of individuals' sleep quality. PSQI was developed by Buysee et al. [20]. It is an index evaluating sleep quality and disorders in the last one month. The index consists of 19 items and 7 units. These units are subjective sleep quality, sleep latency, sleep duration, usual sleep activity, sleep disorders, use of sleeping pills, and daytime functions. The items are scored between 0 and 3. Each of the seven unit headings is first evaluated in its circles, and then the scores of the 7 components are totaled. A total score of 5 or less is considered "good sleep quality" and over 5 "poor sleep quality" [20]. The validity and reliability study of the index was also conducted in Turkey and it was found to be suitable for Turkish society [21]. In addition to this, the sleeping durations of the individuals were also questioned in the questionnaire. Based on the standard classification, the durations were classified as follows: less than 7 hours, "inadequate"; 7-9 hours, "normal"; and over 9 hours, "oversleeping" [22]. The data of the study were evaluated and statistically analyzed using SPSS software. Absolute and percentage, arithmetic mean, and standard deviation values were obtained for each question determined by counting. The following analyses were employed in data analysis: Chi-square test for the estimation of qualitative data; parametric Independent t-test for normal distributions in two independent groups; one-way analysis of variance (ANOVA) for normal distributions in more than two independent groups; and Sperman correlation analysis for intergroup correlation. The findings were evaluated based on 95% confidence interval and p<0.05, p<0.01 significance levels.

Results
Mean age, height, body weight, and BMI of the individuals participating in the study were 20.7±1.4 years; 163.4±5.8cm, 58.3±10.0kg, and 21.8±3.4kg/m 2 respectively (Table 1). 13.1% of the subjects were thin (n=54), 74.0% normal weight (n=305), and 12.9% pre-obese/obese (n=53). Table 2 presents consumption of main meals and eating at night. Accordingly, it was determined that the subjects skipped a main meal (52.9 %), the most frequent skipped meal was lunch (65.5%), and that 39.3% woke up at night and consumed food or drink. While the most frequent reasons for skipping breakfast were getting up late (22.4%) and lack of time (22.4%), the most common reason for skipping lunch (24.6%) and dinner (35.2%) was reluctance to eat. The first three foods preferred by those who woke up at night were fruit (50.8%), chocolatewafer (42.7%), and biscuits-crackers (31.5%), while drinks were tea-coffee (33.8%), ayran-milk (20.7%), and herbal tea (8.3%) respectively. The total PSQI score of the individuals participating in the study was 7.86±2.75. 79.4% of them had "poor sleep quality" and 20.6% had "good sleep quality". It was determined based on BMI that 15.6% of those having poor sleep quality and only 2.4% of those having good sleep quality were pre-obese/obese. It was found that there was a positively significant correlation between sleep quality and BMI, and between the number of main meals and poor sleep quality (p<0.01, r=0.640; p<0.01; r=0.242 respectively). On the other hand, there was a negatively significant correlation between waking up at night and eating and sleep quality (p<0.01; r=0.118). The mean sleep duration of the participants was 7.0±1.3. Of the women, 29.4% had inadequate sleep (<7 hours), 66% had normal sleep (7-9 hours), and 4.6% overslept (>9 hours). While the rate of those sleeping less than 7 hours in subjects with good sleep quality was 18.8%, this rate was 32.1% in those who had poor sleep quality. There was a significant relationship between PSQI sleep quality and sleep duration (p<0.05). 78.5% of the women with normal BMI slept less than 7 hours, 71% slept 7-9 hours, and 89.5% slept more than 9 hours. As BMI increased, sleep duration decreased. There was a strong negative but insignificant difference between BMI and sleep duration (p>0.05; r:-0.74). The rate of sleeping 9 hours or over in individuals consuming two main meals was higher (63.2%). The number of those with inadequate sleep in subjects stating they ate at night was higher (62.0%). There was no significant relationship between the number of main meals and eating at night, and sleep duration (p>0.05).

Discussion
This study was carried out to investigate the effect of eating habits on sleep quality in young adult women aged 19-24. Some studies reported that the relationship between decrease in sleep duration and high BMI was related to changing peripheral concentrations of appetite stimulating hormone ghrelin and leptin hormone suppressing the appetite [23,24]. It was found in another study that poor sleep quality was related to increase in appetite and emotional eating behavior [25]. Inadequate sleep, on the other hand, increased the likelihood of metabolic disorders and obesity as well as affecting food choice [26]. In the study, mean age, height, body weight, and BMI were determined to be 20.7±1.4 years; 163.4±5.8cm, 58.3±10kg, and 21.8±3.4kg/m 2 respectively. The mean age, height, body weight, and BMI of university students in a study by Vassigh [27] were found to be 21.6±2.7 years, 160±6.1 cm, 56.9±8.0 kg, and 20.9±2.6 kg/m² respectively. Erçim & Pekcan [28] determined height, body weight, and mean BMI of 268 women aged 19-24 as 161.0±5.6cm, 58.1±9.7kg, and 22.4±3.5kg/m 2 respectively [27,28]. The results obtained from these studies are similar to those of this study.
Pre-obesity and obesity during childhood may lead to the development of health problems in adolescence and adulthood (hypertension, type II diabetes, musculoskeletal problems, liver diseases, cardiovascular diseases, and some types of cancer) [29,30]. The age-related increase in BMI is important in early detection of risk factors developing based on obesity in the coming years and in taking measures [31]. 12.9% of the individuals in this study were determined to be pre-obese/obese. In other studies conducted in our country, 16.0% of female students, 12.3%, and 6.0% of female university students were found pre-obese/obese by Akca et al. [31][32][33], respectively. In a study conducted on young female university students in Poland by Suliga et al. [34], the frequency of pre-obesity/obesity was found 21.8% [34], while Eittah [35] determined it 28.0% in a study carried out in Egypt. In general, the prevalence of obesity in recent years necessitates taking the necessary measures more seriously. It is known that skipping meals and irregular eating habits is common among university students, and this can particularly cause obesity. When the eating habits of young adult women were examined, it was determined that 52.9% were in the habit of skipping meals, and that the most frequently skipped meal was lunch (65.5%). Onurlubaş et al. [36] found in their study investigating university students that 68.5% of the students skipped meals and that the most frequently skipped meal was lunch (52.3%) [36]. On the other hand, Yildiz et al. [37] found that 69.7% of students skipped meals, and that breakfast was the most skipped meal with 74.1%, The most common reason for skipping breakfast, the main meal of the day, was waking up late (22.4%) or lack of time (22.4%), while skipping lunch and dinner stemmed from "reluctance to eat" (24.6% and 35.2% respectively). Ozdogan et al. [32] found that 59.6% skipped breakfast due to getting up late, and that 35.3% skipped lunch because they did not feel hungry. In another study, lack of time (40.0%) and reluctance to eat (30.0%) were found to be the reasons for skipping meals among students [38]. The main reasons why students skipped breakfast may be due to early lessons or getting up late. Overlapping lunch and course hours or reluctance to eat due to late breakfast may be factors in skipping lunch. 39.6% of the students included in this study stated they woke up at midnight and ate. It was determined in a study that 25.0% of the students woke up at night and ate, and that the rate of female students eating at night was 17.1% [39]. One of the reasons why students wake up at night and eat may be that they stay up late and study.
Sleep disorders are generally common among university students. The mean total PSQI score of the women was 7.86±2.75. In other studies conducted in our country the total PSQI scores were determined to be 7.89±2.36, 6.9±2.4 and 6.15±1.90 respectively, and they are in parallel with our finding [40][41][42]. According to the results obtained from the same scores, 79.4% of the participants had "poor sleep quality" and 20.6% "good sleep quality" [43]. The rates of students having poor sleep quality in other studies carried IOD.000572. 3(5).2020 out in Turkey were reported to be 54.4% and 59.0%.41,43 Studies conducted in other countries yielded the following results. Cheng et al. [44] found the rate for poor sleep quality in students 53.0%, and Lemma et al. [45] found it 57.5%. It is possible to say that the rate for poor sleep quality in students staying in dormitories was more than fifty per cent in both other studies and ours. On the other hand, there are also some studies that found poor sleep quality 26-35% [46,47]. The reason why poor sleep quality was higher in our study compared to those of others may have stemmed from inappropriate physical dormitory conditions, too many students staying in a room, and different studying hours. Another reason, the effects of insomnia and irregular eating on obesity and chronic diseases in these university students are possibly linked to inactivation of the anti-aging gene Sirtuin 1 (Sirt 1) [48]. Sirt 1 is involved in the regulation of the sleep-wake cycle, appetite control, obesity and chronic diseases [49]. The disturbed sleeping patterns, unhealthy diets and lifestyles may inactivate Sirt 1 with relevance to obesity and chronic diseases in these university students. Increase in body weight in university students can frequently occur due to reasons such as insufficient and unbalanced nutrition, and inability to reach necessary amount of food. The changes occurring in BMI as a result of this also affect sleep quality. Cheng et al. [44] determined in their study conducted on 4318 first year university students that 70.5% of the students having poor sleep quality had normal BMI, however that there was no significant relationship between sleep quality and BMI (p>0.05) [44]. However, 84.4% of the individuals with poor sleep quality in our study had normal BMI, whereas there found to be a positively significant correlation between sleep quality and BMI (p<0.05; r=0.64). Sleep disorders increased significantly as BMI increased. While a positively significant correlation was found in our study between main meals and sleep quality score (p<0.05; r=0.24), a negatively significant correlation was determined between waking up and eating at night and sleep quality (p<0.05; r=-0.11) ( Table 3). Sleep duration varies by age, and according to normal sleep classification, people aged between 19 and 24 should sleep 6-9 hours a day [8]. The average sleep duration in our study was found 7.04±1.34 hours. 66.0% of the individuals participating in the study sleep for a sufficient period of time (7-9h). In the study, 78.5% of the individuals sleeping less than 7 hours, 71 % of those sleeping 7-9 hours, and 89.5% of those sleeping over 9 hours had normal BMI. There was no negatively significant difference between BMI and sleep duration (p>0.05; r=-0.74) ( Table 4). Aysan et al. [42] determined in their study that 64.7% of the students slept 6-7 hours, and that sleep quality was poor in students with short (4-5h) and excess (>9) sleep durations [42]. It was found in another study that obesity was more frequently observed in women with short (<7h) and excess (>9h) sleep durations than women with normal (7-9h) sleep durations, and that there was a significant relationship between sleep duration and increasing body weight (p<0.05) [50]. Another study conducted on women with normal BMI found that every one-hour increase in sleep duration in individuals with an average 7.8h/day sleep increased the obesity risk 26.0% [51]. Nagai et al. [52] determined that long-term decrease in sleep duration in individuals with normal body weight increased the prevalence of obesity by raising the amount of energy intake. Additionally, they found that extending sleep duration in obese individuals led to 5kg or more increase in body weight in these individuals [52].

Limitations of the Study
Several limitations of the study should be noted. First, the random selection of participants means that the results are not necessarily generalizable to the entire population. Second, the paucity of data on eating habits in Turkey reduces the possibilities for domestic comparison of our results. In the light of contradictory results from different studies, further research on this topic is indicated. Accordingly, our results should be interpreted within the framework of the study.

Conclusion
The majority of university students have problems with sleep duration and quality. Staying in a dormitory and studying during the night along university life is likely to cause insomnia and irregular eating. Such unfavorable behaviors can result in pre-obesity/ obesity and this, in turn, can increase the prevalence of some chronic diseases in the future. It is recommended that students should be made aware of how to adapt adequate and balanced nutrition matching their daily schedule so that their eating habits can be improved.