For the past few decades, scientists and medical researchers have been working hard to crack the snooze code said to be responsible for a major chunk of lifestyle diseases, mainly diabetes and obesity.
For an average person, sleep means nothing more than a brief period of inactivity each night to recharge themselves for the next day. However, numerous research and surveys conducted over the past two decades on patients with diabetes and other stress-related complications have revealed that almost all of them were either obese, sleep deprived or both.
This has forced experts to conclude that sleep deprivation could be the square one destination that leads to obesity, type 2 diabetes and even life-threatening cardiovascular diseases.
“Type 2 diabetes mellitus (T2DM) has been shown to be associated with higher incidence of sleep disorders, which may be due to the disease itself or because of secondary complications or associated comorbidities associated with diabetes,” Dr DM Mahesh, consultant, endocrinology, Aster CMI Hospital, Bengaluru, India, told Happiest Health. “On the other hand, shorter sleep duration and erratic sleep behaviour itself have been linked with higher incidence of obesity, metabolic syndrome and T2DM.”
He also pointed out that conditions like obstructive sleep apnoea (OSA) could lead to oxidative stress and a spike in inflammatory marker activity which could heighten the risk of cardiovascular diseases. OSA is a condition when upper airways become obstructed, leading to sleep-disrupting breathing problems.
Dr Banshi Saboo, Ahmedabad-based diabetologist and secretary, Diabetes India, told Happiest Health that sleep was intrinsically associated with diabetes and other cardiovascular conditions. He said that those affected with type 2 diabetes could have their glucose levels affected if they are not getting adequate sleep and subsequent internal vascular interactions.
“There is an umbrella term called Syndrome Z to define this,” Dr Saboo said. “Basically, this defines how sleep disruptions caused due to OSA are directly linked with vascular conditions like blood pressure, insulin resistance, cholesterol, and obesity. The oxidative stress and internal vascular changes triggered by these factors are interlinked as it can result in multiple conditions, including diabetes.”
With the emergence of big data and information-trawling algorithms, data scientists and coders have also started compiling and collating all available information on sleep studies, glucose tolerance, obesity and stress to trace any common pattern linking them with each other.
Most such research tends to be focused on the impact of sleep deprivation on energy homeostasis (self-regulatory body functions to ensure better health and survival of an organism), insulin resistance (underlying reason for diabetes that could also trigger obesity) and beta-cell functionality (pancreas and insulin production).
One study even indicates that there is a direct link between sleep deprivation and neural impulses that make people generally preferring healthy food to choose high-calorie junk food when deprived of adequate sleep. Its main objective is to establish how neuron clusters in the cortical region of the brain of sleep-deprived individuals tend to go into an overdrive and ‘tempt’ them to gorge on high-calorie food.
“Stress eating at night after work hours is a very common among salaried professionals,” says Rajeesh Kumar, a Kochi-based health coach and nutrition expert. “I always ask them to ensure that they get more than six hours of sleep without fail. Quite often people strictly adhere to their diet and workout for hours, but often fail to meet their fitness goals because of their poor sleep cycle.”
In 2014, the US government’s Centers for Disease Control and Prevention (CDC) stressed the need to address sleep disorders after it was found that at least 45 per cent of Americans were sleep-deprived and stressed out with less than seven hours of sleep on a daily basis. The CDC said this on the basis of a 2013 nationwide survey conducted through its Behavioral Risk Factor Surveillance System.
The CDC commissioned multiple studies on the impact of sleep deprivation and other health conditions – mainly obesity, diabetes and heart attacks. It also started to list sleep deprivation as one of the five key chronic disease-prevention factors to be adopted to ensure a long healthy life alongside a strict no-smoking protocol, total avoidance or moderate consumption of alcohol, ensuring minimum physical activity daily and maintaining a healthy body weight.
Notably, there is a clear-cut demarcation between sleep deprivation and sleep disorders. The latter and its variants – such as apnoea and insomnia – are often categorised as medical conditions, whereas sleep deprivation could be due to both medical and lifestyle reasons.
Sleep deprivation, binge snacking and obesity
Many of us remember often arguing with our parents as children when asked to turn off our bedroom lights and crash for the day by 11pm. Research has now proven beyond doubt that adequate sleep is not just an act of relaxation but an absolute necessity to stay fit and healthy. Researchers from Helen Wills Neuroscience Institute, University of California, conducted a study in which they claimed to have found a possible link between binge eating of calorie-rich snacks and cerebral neural impulses in sleep-deprived people that could lead to obesity.
The main objective of the study was to establish a link among food craving, desirability and sleep disorders. The researchers roped in 23 volunteers, recorded their dietary habits and monitored their sleep patterns with and without disruptions. Functional MRI scans were conducted and electroencephalography (brain wave) readings were recorded both in normal and sleep-deprived states. It was found that functioning of the neuron clusters in frontal cortex regions of the human brain (that help us analyze and evaluate before making choices and decisions) decreased considerably due to sleep deprivation. This was inversely compensated by an increase in neural activity in two neuron clusters in the brain’s limbic system – the amygdala neuron cluster and the ones in the ventral striatum that are generally responsible for making sudden impulsive and emotional decisions.
The volunteers were served a standard breakfast on the day of the lab tests when they had to sleep without any interruption and their neural and brain waves were mapped at the lab along with blood-oxygen levels, breathing patterns and limb movements. They were monitored by staff at the lab to ensure that they stayed awake and were not asleep when the readings were recorded for their sleep-deprived state. The volunteers were shown 80 food items and asked to rate them on a scale of 1 to 4 depending on their urge to eat them.
It was found that they always preferred food with high-calorie content when they were sleep deprived rather than healthy food. The neural readings also confirmed that almost all of them had heightened activity in the neuron cluster responsible for impulsive emotional decisions, forcing them to choose unhealthy food items. Their regular diet and sleep patterns were monitored and recorded at least three days before the lab tests to ensure that they were all well rested and not affected by any other external factors.
Another functional MRI study conducted in 2012 on these same cortical regions of the brain by researchers from the Montreal Neurological Institute found that food cues generated by the neural clusters in human brain are similar to cravings for addictive substances such as nicotine.
Experts say this could explain why people often become addicted to unhealthy eating habits, especially during night hours, leading to obesity and other lifestyle issues.
“It also depends on the availability of food items at your home. After all, one cannot eat when one is asleep. So, people with a longer sleep cycle will ultimately end up eating less,” says Bibin Edakkara, a fitness enthusiast employed in the United Arab Emirates. After moving to Dubai, Bibin had gained 60kg in four years mainly due to a lack of sleep and stress binge-eating at night.
Another study published in the Lancet in December 2017 – a global analysis of body mass index and body measurement evaluations in about 18.9 million individuals including adolescents – indicated that obesity prevalence shot up from 0.7 to 5.6 per cent among girls and from 0.9 to 7.8 per cent in boys between the years 1975 and 2016. Among adults it was found to have surged from 4.7 to 13.1 per cent during the same duration. Sleep duration was one of the major contributors for this alarming surge.
Inadequate sleep and excess blood glucose levels
If one goes by the simple logic that sleep deprivation leads to obesity, stress, hypertension and other factors that often interfere with insulin resistance and pancreatic functions, then it will also definitely impact blood glucose levels. The same holds true in the case of individuals suffering from sleep disorders, including insomnia, sleep apnoea and circadian rhythm disorders (sleep and wake-up cycle).
Numerous studies, research reviews and articles have indicated a direct link between sleep deprivation and various isolated factors that trigger diabetes, including obesity, insulin resistance and glucose metabolism.
One of the numerous studies conducted to establish the link between sleep disorder and abnormal blood glucose tolerance, which could lead to a full-blown condition of type 2 diabetes, includes the findings of the Children’s Sleep and Development Medical Research Centre in Hyogo, Japan in 2020. After blood glucose levels of 124 patients affected with Circadian Rhythm Sleep-Wake Disorder (CRSWD) were evaluated, as many as 25.8 per cent of them were found to have abnormal glucose tolerance. The CRSWD is a prominent sleep disorder in which the affected individual end ups sleeping and waking at odd hours since their internal wake-up and sleep cycle is not in sync with the external day and night cycles.