Exploring The Connection Between Sleep, Obesity And The Gut Biome


 

Obesity is widely prevalent and has been shown to be a major factor in the development of non-communicable diseases such as cardiovascular illness and diabetes. According to the Centers for Disease Control and Prevention (2015-2016 data), the prevalence of obesity was 39.8% in U.S. adults and 18.5% in U.S. youth. 

Obesity is associated with several co-morbidities such as

  • Type 2 diabetes mellitus
  • Heart disease
  • Stroke
  • Obstructive sleep apnea
  • Hypogonadism
  • Premature death

Obesity can be a fallout of poor sleep

All mammals need sleep for optimal development and functioning, and spend a significant chunk of their life asleep. Yet for we humans, in recent times our average sleep duration has shrunk from 8 to about 6.5 hours a night, according to a CDC Report.

We are working longer hours and are constantly connected thanks to the internet, laptops, and smartphones. We’re also dealing with increased social demands and spending more time bathed in artificial light, all of which disrupts our circadian rhythms - our internal clock. 

Sleep deprivation is known to disrupt multiple systems within the body, some of which are the first steps on the path to obesity. In fact, the same CDC report also states that sleep deprivation increases the chances of being obese by about 33%, just as a standalone factor.

Animal studies have shown that sleep deprivation causes rapid alteration of gut microbiota.

Moreover, sleep restriction in humans:

  • Stimulates appetite, promoting overeating when food is available
  • Increases hunger and food-based reward system in the brain 
  • Is associated with reduced exercise.

Needless to say, all of these factors place a huge premium on sleep.

The brain-gut-adipocyte relationship

When the brain-gut-adipocyte interactions are optimal, there is an equilibrium amongst energy, body fat, and body weight. Any disruption or adverse changes in their communication pathways can lead to an imbalance between energy intake and expenditure, culminating in obesity.

On a physiological level, sleep deprivation triggers abnormal activation of sympathetic neurons.

Changes occur in the brain, such as:

  • Lack of inhibition of neuropeptide Y neurons in the hypothalamus region of the brain
  • Dysregulation of melanocortin receptors in the forebrain and hindbrain
  • Overactivation of orexin receptors

These changes add up to decreased sensitivity to insulin, which,  in turn, leads to obesity.

Sleep deprivation also correlates with an increase in serum orexigenic hormones (such as ghrelin) and a decrease in anorexigenic hormones (such as leptin). Imbalance in these hormones increases hunger and cravings for carbohydrate-rich foods.

The link between hypertension, obstructive sleep apnea, and obesity

Obstructive sleep apnea syndrome (OSAS) is the most common cause of secondary hypertension. 75% of treatment-resistant hypertension cases also show the presence of OSAS. Research in animal models has shown that intermittent hypoxia models lead to gut dysbiosis.

Components of the gut microbiota contribute to control of blood pressure (BP); therefore, gut dysbiosis caused by obesity might also lead to increased BP.

Gut microbiota, sleep, and circadian rhythms

The circadian timing system i.e. our internal biological clock drives metabolic and hormonal pathways, bile acid formation and immune/ inflammatory processes. Tied in with behavioral cycles and environmental stimuli, this system influences mechanisms crucial to preventing obesity, type-2 diabetes, and metabolic syndrome. 

A higher incidence of these diseases is seen in night shift workers. Circadian misalignment, altered meal timings, ill-advised food choices (nightly cravings typically revolve around snacks, fast foods, and sugary foods)  and the diurnal variation of energy metabolism are all contributing factors.

Factors that impact our circadian-metabolic axis, such as light/darkness cycles, sleep/wake cycles, and diet/eating patterns also influence the daily rhythms of our gut bacteria. In particular, they can alter the composition, localization, and functions of gut bacteria, which have their own special ecosystems. 

Gut bacteria can influence our daily rhythms via their metabolites: butyrate, polyphenolic derivatives, vitamins, and amines. Sleep deprivation-related disruptions to microbiota affect energy use and regulation in the host, at least partially contributing to an increased risk of obesity and metabolic syndrome.

Getting adequate sleep is essential for one’s health but getting enough hours is often neglected, especially during times of high stress.  

When it comes to sleep habits, consistency is your friend. Also, aligning meals and sleep according to circadian rhythms, and incorporating regular daytime exercise is crucial. 

It helps restore disrupted circadian rhythms and improves chances in the fight against obesity and related comorbidities. Ensuring that you get enough and good enough sleep is multifactorial, exercising, keeping a regular schedule, eating well, managing stress...but the benefits are multifactorial too, helping keep your gut health, giving your brain respite, and staving off obesity and its related co-morbidities.

Don't neglect those zzzzzs, and we wish you a restful sleep!

Author: Ranjan Sinha


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