Obesity and Sleep: How They Affect Each Other

Recent research indicates that there has been a rise in obesity cases since 1980. In fact, the prevalence has been found to have doubled. In modern society, the doubling of these figures has been precipitated by a number of factors which are but not limited to reduced sleeping hours which result into lack of quality sleep, which results from loss of sleep. The growing knowledge of research indicates that that short duration of sleep is the greatest risk factor to obesity and its related complications. Short durations of sleep among adults which lasts 5 hours or less has been noted to be a predisposing factor. Despite this, the correlation betwixt the obesity and time of sleep hours has faced heavy criticism and rendered quite misleading due to the weak study designs used, the application of self-reported outcomes of height and weight, and small sample sizes used. In as much as recent longitudinal designs have been able to counter the weaknesses in the designs in earlier studies, findings still bear controversy. In a research done by Strangers et al, there was no correlation betwixt increase in the body mass and short sleep duration. Watanabe et al conducted a similar research among the Japanese over a period of one year and observed increased BMI among the male population compared to their female counterparts who claimed to be self-reported short sleepers over the study period. 

Comparing these studies is difficult since it poses great differences due disparities in the time frame and race used to follow up the results. In order to determine whether the results would be different if the follow-up period would be extended further, Patel et al conducted the same research over a period of four years among the Japanese workers. His findings revealed a greater increase in the weight among the short sleepers. This was consistent with the findings of Watanabe et al. 

Sleep is a process which restores the brain. It is evident that the health of the entire body depends on the quality of sleep one gets ( Nishiura & Hashimoto, 2010) . The reduced sleeping durations in this modern generation because of work related issues has become a precursor to the many complications we have witnessed.in modern times, behavioral curtailment of sleep is increasingly becoming a habit. Our society is increasingly transforming into a 24-hour economy in which work and leisure is done in the evening thus making people sacrifice hours meant for sleep ( Kobayashi et al., 2012) . Such behavioral changes have major impacts on the sleeping time, duration of exposure to the dark, and the general organization of the cardiac rhythms as a result of exposure to artificial lights after the sun has set. This leads to late bedtimes, reduction in the total hours spent sleeping, and the opportunity to eat food during the normal day hours when the sun has not yet set ( Magee, Reddy, Robinson & McGregor, 2016) . This has not only affected mental health but also the person’s health in general. This study therefore is aimed at investigating the relationship between obesity and sleep. 

The purpose of this paper is to investigate the existence of a bidirectional association betwixt low quality of sleep, deranged eating habits, and high mass. The available research shows the relationship betwixt the presence of obesity or overweight and poor sleeping standard. While the quality of sleep seems to be a wide term, it involves the length of sleep, the frustration in getting asleep or keeping asleep as well as applying of medications which enhance sleep (Buysse, Reynolds, Monk, Berman & Kupfer, 1989). In this study, Pittsburgh Sleep Quality Index (PSQI) in order to determine the quality of sleep is used. PSQI is a widely and effectively utilized self-reported instrument which has high reliability and validity in giving out data. It contains questions that have been formulated which are easily answerable and understandable (Buysse et al., 1989; Smyth, 1999). PSQI determines subjective quality of sleep in seven different areas which include but are not limited to latency of sleep and the duration of sleep (Krystal& Edinger, 2008; Smyth, 1999). 

Literature review 

Until now, about 50 epidemiological studies have been conducted in different regions all of which have investigated the correlation betwixt sleep and obesity in children and adults. One of the areas of interest of this research is relationship BMI and PSQ, in other words being obese or overweight. World Health organization classifies a BMI of ≥25 as overweight and ≥30 is an indication of obesity in a person. The available evidence relates high BMI (Hbmi) and PSQ. Longitudinal studies for example and studies which featured mixed races and socioeconomically diverse groups of people found out catching sleep for <7 hours a day encountering difficulty catching sleep or keeping sleepy for some time was largely correlated with high BMI (Gangwisch, Malaspina, Boden-Albala& Heymsfield, 2005; Meyer, Wall, Larson, Laska & Neumark-sztainer, 2012). Further results obtained from studies on which are cross-sectional and which contained samples with a mixture of races indicated that obese people have a tendency of sleeping for less hours compared to the non-obese individuals. Furthermore, the research established that for every hour of lack of sleep, the likelihood to get obesity increases by 80%. Similarly, PSQ was also found by the study to decrease the physical activity of the body which is highly associated with BMI (Cappuccio et al., 2008; Gupta, Mueller, Chan & Meininger, 2002). 

The limited number of studies that have so far attempted to give an explanation on the existing connection between PSQ and high body mass index established that sleep apnea may be useful in mediating the correlation (Yeh & Brown, 2014). Sleep apnea is the disturbance caused to sleep as a result of continued interruptions to the flow of air via mouth and nose in a minimum of thirty instances during a period of 7 hours of sleeping period (Guilleminault, Tilkian & Dement, 1976). Despite this, sleep apnea is a slightly rare phenomenon in individuals (Tishler, Larkin, Schulchter &Redline, 2003) in as much as PSQ is a prevalent phenomenon (Buysse, Reynolds, Monk, Berman & Kupfer, 1989). Thus, it can be said that it is only a small population high BMI people who have PSQ who have complications with sleep and other probable justifications for the relationship betwixt PSQ and hBMI may be available (Yeh & Brown, 2014). 

Since there lacks studies which have further tried to find out the factors which may facilitate the association betwixt high BMI and PSQ, this particular research tries study it by determining if disorderly eating arbitrates this correlation. Disorderly eating refers to night time eating and binge eating. Binge eating (BE) is the consumption of huge portions of food over a short time frame and the failure to regulate ones’ eating behavior (Johnson, Carr-Nangle, Nangle, Antony & Zayfert, 1997). The research make use of binge eating scales (BES)- a questionnaire determines if and to by how much one binges through asking about their tendencies of eating (Gormally, Black, Daston& Rardin, 1982). On the other hand, night-time eating (NTE) makes reference to the consumption >25% twice a week of caloric consumption after dinner or waking up at night (Allison et al., 2010; Stunkard, Grace&Wolff). The research therefore makes use of the Night-time Eating Questionnaire (NEQ) to find out if the degree in which victims engage in NTE behavior (Striegel-Moore, Franko & Garcia, 2009). 

As observed by Yeh and Brown (2014), the inability to fall sleepy and having low lengths of time sleeping give hBMI victims extra time and opportunities to eat, thus, causing gain of weight over time. This observation is in agreement with Andersen, Stunkard, Sorenson, Peterson and Heitmann (2004) and Crispim, Zimberg, dos Reis, Tufik and de Mello (2011), who both established that NTE was correlated with the gain of weight and PSQ in hBMI individuals. On the same note, research has found out that BE is related with PSQ and hBMI in obese people (Yeh & Brown, 2014). 

Due to this, unavailability of studies examining possible correlations of the relationship betwixt hBMI and PSQ and studies showing the relationship betwixt disorderly eating and hBMI and PSQ, this research seeks find out if eating which is disorderly (NTE and BE) agrees with the association betwixt hBMI and PSQ. The hypothesis for this research included: (a) wrong quality of sleep and eating which is disorderly will be related to high BMI; and, (b) hBMI and disorderly eating will be related with higher instances of wrong quality of sleeping. 

Methodology 

Participants 

The participants of the research were recruited through an advertisement which was place In the University and other online platforms. The inclusion criteria into the study was that someone had to be aged 18 years and above and having a BMI of 18.5 (normal weight) or more. A total of 678 people took part in the study however, only data from 330 participants was included in the study because the rest did not match the study requirements or they did not complete the study for their results to be included in the study. Out of the 330 whose results were used to determine the study outcome, 107 (32.4%) were of the male gender while 223 (67.6%) were of the female gender. The age of the participants ranged between 18-87 years. Their mean age was calculated to be 27.42 years ( SD =10.36). 

Procedure 

Those who took part were able to access the study through the URL which was embedded within the advert. All who secured the study requirements and agreed to take part gave their responses in the online questionnaire which asked about: their resent sleeping and eating experiences. It also sought to ask them about their weight and height, to calculate their BMI. SPSS statistical software (version 22) was used to compute statistical analysis. The two hypotheses were tested using two standards multiple regression analysis. 

Materials 

The study collected demographics which included the level of education. The BMI was also computed and calculated by computing the weight of the participants (in kg) and their height (in m). A BMI indicating ≥25 indicated overweight while that of ≥30 showed obesity. Seven subjective domains of sleep were assessed by the PSQI. Overall, a PSQI score (ranging from 0-21) of >5 was an indication of moderate to severe difficulties in sleeping the general score of sleep contains a high internal consistency reliability with a Cronbach’s α of 0.83 (Smith & Wegener, 2003). The third thing is that BE, was tested with the use of BES that was made up of 16 items which showed behaviors connected to eating. The general binge eating scale score which ranged from 0 to 46 of >27 demonstrated BE and a generally high score was an evidence of even worse BE. BES in this study had an overall higher agreement with a Cronbach’s α of 0.92. The final step involved the measuring of NTE using the NEQ which had a total of 15 questions. An overall range from 0 to 52 NEQ score of >25 was evidence of NTE behavior. The NTE in this study was in tandem with a Cronbach’s alpha of 0.73. 

Outcomes 

During the study, several deviations were identified for every variable used. Despite that, not even one of the outliers was ruled out since they only represented authentic cases. Kolmogorov-Smirnov statistics of general quality of sleep, BE, body mass index and night time eating were all established to be non-significant (i.e., p < 0.05. This demonstrates there was a normal distribution of these key variables. 

Multiple regression analysis was conducted twice in order to find out: (a) PSQ and eating which is disorderly (binge eating and night time eating) which were related with hBMI; and (b) if hBMI and eating which is disorderly (binge eating and night time eating) had any relationship with the higher scores of PSQ. The standard deviation and means of important variables were indicated in table (i). 

Variable	Mean	Standard Deviation
Body Max Index (BMI)	26.08.	8.55.
Total sleep quality score (PSQI)	6.37.	3.66.
Binge Eating Scale Score (BES)	13.78.	10.25.
Night Eating Questionnaire Score (NEQ)	14.60.	6.85.

NB: N­=330 

In the first regression analysis, it was revealed that the overall PSQ and BE had a positive association with high BMI (dependent variable) thus accounting for a significant 8% of the variability in BMI, R 2 ­ = 0.80, when adjusted, R2 =0 .071, P = 0.000, F (3326) = 9.40. Examining beta weights revealed that the major contributor to high BMI was Binge eating (see table ii). Table ii contains the standardized (B) and the unstandardized ( β) regression coefficients for each predictor in the regression model. 

Table ii 

Regression coefficients for (B) and (β) demonstrating hBMI 

Variable	B (95% C.L)	Β
Total quality of sleep	0.399	0.171
BE	0.118	0.142*
NE	0.033	0.026

Note: N =330 

C.L refer to the confidence level 

*p < 0.05 

In the second MRA, it was established that PSQ (dependent variable) was associated with a high BMI and NTE (but not BE). This accounted for 35.6% of the total variability in the overall PSQ, R2 = .356. When slight adjustments were done, R2 of the total variability in the overall PSQ, R2 = 0.350, F *3326) = 59.99, p = 0.000. 

Regression coefficients of (B) and (β) for each predicting factor 

Table iii 

Variable	B (95% C.L)	Β
BMI	0.051	0.120*
Binge eating	0.267	0.500
Night eating	0.032	0.090*

NB : N= 330 while C.L is the level of confidence 

*P <0 .05 

Discussion  

The aim of this study was to establish whether eating which is disordered (NTE and BE) elucidates the connection between PSQ and hBMI. The results which showed that PSQ and BE had some relationship and association with hBMI supported the first hypothesis of this study. Other results showing the positive relationship between hBMI and NTE (but not BE) with PSQ supported the second hypothesis of this study. 

To begin with, this study established the existence of a bidirectional connection betwixt PSQ and high BMI which is agrees with studies that had established that: (a) hBMI was associated with sleeping <7 sleeping hours or having troubling falling asleep or keeping asleep; (b) shorter sleeping hours are experienced by obese individuals compared to their non-obese counterparts who experience shorter durations of sleep; and (C) the risk of obesity is increased by 80% for every hour of sleep lost; (Cappuccio, et al., 2008; Gangwisch, Malaspina, Boden-Albala& Heymsfield, 2005; Gupta, Mueller, Chan & Meininger, 2002). The second finding established that BE was associated with hBMI. This was consistent with the findings of Yeh and Brown (2014) who found in their meta-analysis that binge eating had a positive correlation with high BMI. Another revelation of this study indicated that NTE bared a direct relationship with PSQ. This was consistent with the findings of Crispim, Zimberg, dos Reis, Tufik and de Mello (2011) who established that NTE had an association with PSQ. The findings did not however, support the hypothesis of the study which included: Night time eating is correlated with hBMI and binge eating, and is related to PSQ. The results agree with those established by Andersen, Stunkard, Sorenson, Peterson and Heitmann (2004) who both established the relationship between NTE, weight gain and the people with high BMI and Yeh and Brown (2014) whose findings established the correlation between binge eating and PSQ. 

On a broad perspective, the findings agree with the available findings in literature and the theories which all point to the availability of a positive bidirectional relationship between hBMI and PSQ. BE has a positive relationship with hBMI while NTE has a positive relationship with PSQ. Despite the findings, it is also likely that alternative explanations to the results of this study exist which may have in one way or the other influenced the outcomes. To begin with, the first limitation of this study is that most of the respondents and participants were females who were well educated and who bared normal weight. It therefore poses difficulty in terms of generalizing the results to a population which contained mixed gender. It would also be impossible to generalize these findings to a population with a mixture of well and less-educated individuals. The second limitation is that the findings are only based on the self-reported measures of sleep quality, eating behavior and BMI. The problem with this approach is that people may submit inaccurate information due to inability to respond to specific questions or even deliberately lying in their responses. The last limitation is access to the internet. This study required that the participant is able to access an internet connection. This eliminated those people who could not access internet easily or who are not technology oriented. 

Generally, the implications of this study tend to encourage individuals to do everything in their capacity to improve their eating and sleeping habits since they seem to in a big way affect each other. As a result, obese and overweight individuals should have an intake of a calorie-restricted diet. Such would include women taking 1200-1500 kcal/d while men taking 1500-1800 kcal/d. It also encourages people to control their NTE because of its association with PSQ. Adults with a BMI ≥ 40 kg/m 2 or ≥ 35 kg/m 2 with conditions related to obesity and who have the motivation to lose weight should respond to behavioral treatment in order to achieve weight loss. This study also proposes that individuals with a BMI < 35 kg/m 2 should avoid in as much as they can undergoing bariatric surgical procedures. Similarly, this study seeks to encourage people to adopt healthy sleeping mechanism by having enough of sleeping time. On average, adults should sleep a minimum of seven hours a day while children should sleep for a minimum of nine hours a day. 

As a result of the limitations associated with this study, future research could seek to include: samples with mixed gender (with equal representation of participants), adopting the use of paper-based questionnaires as opposed to the online questionnaires and using objective measures of BMI, eating and sleep quality behavior methods as opposed to subjective or self-based reports method. If these suggestions are adopted in future researches, then it will mean that it will be easy to generalize the findings to the general population and that it will ensure a more accurate measures of key variables in the study. 

This study in conclusion, sought to investigate if sleep quality which is poor and disordered eating (binge eating and night time eating) had any significant association with high BMI. In addition, it also sought to find out whether high BMI and disordered eating (but not night time eating) had any positive association with general poor sleep quality. The findings are significant since they provide helpful implications for an individual’s healthy behavior as well as future research. Further research is required so as to include mixed gender. There should also be a balance in the gender representation in further studies so as to ensure the findings can be generalized in all populations. 

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