Lack of sleep will lead to weight gain

“The best bridge between despair and hope is a good night’s sleep,” goes a popular saying. This article provides insights about sleep deprivation and weight gain.

While it is a common notion that lack of sleep can affect one’s concentration, it also turns out that it can have a significant influence of weight loss, gain, and stability.

Experts say that sleep deprivation is an escalating issue, particularly in the younger population and not getting enough shut-eye can affect a person’s mental and physical well-being. Cognitive and psychological consequences of sleep deprivation may lead a person to choose unhealthy food options (e.g., extra bottle of soda, sugary dessert nightcap) or have decreased regulation of appetite, while at the same time decreasing motivation and energy as a consequence of insufficient sleep may lead to reductions in physical activity that also contribute to weight gain. Thus, having good sleep health is a controllable factor that has the potentially to significantly impact one’s likelihood for developing obesity.

But what are the reasons for the hunger pangs? One reason could be a disruption in the appetite hormones. Ghrelin regulates the feeling of hunger and leptin regulates the feeling of satisfaction. According to the review paper titled ‘Sleep deprivation and obesity in adults: a brief narrative review’, leptin is released from the adipose tissue (fat) and acts on the receptors in the hypothalamus of the brain, where it inhibits appetite and promotes satiety, thus limiting food intake. Circulating blood levels of leptin are proportional to body fat mass.

Ghrelin, however, is released from the stomach and pancreas and stimulates appetite. Circulating ghrelin levels fluctuate in response to food intake. Sleep deprivation causes leptin to decrease and ghrelin to increase.

‘Sleep Deprivation: Effects on Weight Loss and Weight Loss Maintenance,’ a study published in the journal Nutrients on April 8, 2022, reveals that short sleep duration is reported to be associated with higher energy intake, due to increased consumption of saturated fat, resulting in weight gain and an increase in BMI.

Jesse Cook, MS, clinical psychology PhD student, University of Wisconsin, Madison, USA, talks more about the relationship between sleep and metabolism, in a telephonic interaction with Happiest Health. “Sleep health and metabolic health share a bidirectional relationship whereby sleep health problems can lead to a heightened risk for developing or exacerbate the severity of metabolic health problems and vice-versa. Dr Christopher Depner and colleagues published an eloquent review in 2014 on the topic that saliently captures this important, bidirectional relationship in their paper titled, ‘Metabolic consequences of sleep and circadian disorders.’ In this review, they highlight how sleep health problems, such as insufficient sleep duration, as well as sleep disorders, such as insomnia and obstructive sleep apnea, influence metabolic problems like obesity and type 2 diabetes. Since sleep regulates many aspects of human physiology that are critically important for normal metabolic function, poor sleep health can result in dysregulation of hunger hormones, patterns of energy expenditure and biology involved in energy metabolism that heightens the risk for the development of metabolic problems,” he says.

“There is a wealth of other literature that recognises the importance of sleep on health. For example, Reutrakul and Van Cauter, in 2018, published a similar review unpacking sleep’s influence on obesity, insulin resistance and risk of type 2 diabetes. Like Depner and colleagues, they highlight the deleterious impact of poor sleep health on the regulation of hunger hormones, energy expenditure and glucose metabolism, yet they also draw attention to the brain changes that occur in response to poor sleep that impact appetite regulation,” adds Cook.

Sleep deprivation due to light is linked with weight gain

“Most people do not understand the relationship between sleep and weight. Just like other creatures, our behaviours are linked to our environment. Sleep and weight are important aspects of this equation. Light is yet another aspect that plays a role in this equation. Our exposure to light is associated with the circadian rhythm, which we call the biological clock. This rhythm dictates what hormones and chemicals are released in our bodies. This also dictates when we should eat and decides our appetite,” says Dr Ravichandra MRK, consultant, pulmonology, Narayana Health City, Bengaluru.

He says that any disturbance in this rhythm affects sleep and disrupts weight. Elaborating on the phenomenon, he says, “our brain responds to light. Earlier studies had established a relationship between light, sleep and weight gain. This was best explained by a study on how TV affects sleep and leads to weight gain. When people watched long hours of TV, they skipped their sleep and ended up eating a lot, which led to weight gain.”

The doctor explains that since our brain is designed to react to light. Whenever we are exposed to bright or blue light, it creates an appetite in the body and we start to hunt for food. “The hormones leptin and ghrelin dictate when we have an appetite and when we do not. When ambient lights are on, the melatonin (the hormone that controls the sleep-wake cycle) starts increasing and tells the brain that the light is low and you need to sleep. There is a complex interplay of hormones that are secreted from various parts of the body. When individuals are exposed to bright light at an unusual time, that is when the problem starts,” points out Dr Ravichandra.

He says, for example, when an individual is texting or using their mobile phone in the middle of the night, ghrelin is secreted because of the light emitted from the phone screen. This triggers an unusual hunger appetite and one ends up eating junk food. This, in turn, causes the melatonin levels to dip and as a consequence, the individual tends to get sleep deprived.

Sleep apnoea and weight gain

“People with sleep apnoea find it difficult to catch a sound sleep because of blocked nasal airways. The after-effect of this is daytime drowsiness, fatigue and lethargy. When sleep-deprived people do not get enough physical activity, their water and salt content remain in the body, leading them to gain weight,” says Dr Satyanarayana Mysore, head of department, pulmonology and sleep, Manipal Hospital, Bengaluru.

So, when do people lose weight? “Only when they get enough sleep and follow a proper dietary lifestyle with exercise, will people lose excess weight and maintain good health,” he says, adding that people who are interested in maintaining their good health and exercising regularly are more likely to also get a good night’s sleep. “This doesn’t mean you have to force yourself to sleep; all you need to do is follow healthy habits that keep you fresh after you wake up from sleep even if it is less than seven hours of sleep,” he suggests.

“While it is understood that people with sleep apnoea issues are prone to gaining weight, there is also a link with hyperthyroidism. Obstructive sleep apnoea is usually present in people with this condition. It propels them to gain weight as they tend to be less active due to inadequate sleep. This condition keeps deteriorating if not diagnosed early. One should address this (sleep apnoea) on time so that doctors can give them therapy like continuous positive airway pressure (CPAP), which will help them sleep better,” says Dr Y A Sheriff, a pulmonologist from Bengaluru.

Dr Sheriff highlights the importance of CPAP. “When CPAP therapy is given, and people tend to sleep well, automatically their metabolism becomes good. They wake up fresh and have the bandwidth to exercise and go about their daily activities, enabling them to lose weight. More likely, people will be happy when they walk every day or do some exercise and follow a proper diet,” he says.

Sleeplessness, pre-diabetes and cardiovascular risks

Dr Mahesh DM, consultant-endocrinology, Aster CMI Hospital, Bengaluru, points out that increased stress hormones could be a probable cause of weight gain. He says, “While a sound sleep cycle is one of the primary aspects of weight management, stress hormones released in the body also have a big part to play in an individual’s weight management journey. Between 4 am and 8 am, stress hormones increase. These hormones see a dip when we are asleep. When you are stressed, do not sleep at night and it becomes a habit, the stress hormones increase automatically leading to weight gain. The steroid hormone, cortisol, also tends to be high in such cases. Eating habits too undergo a change. For example, an individual develops a pattern of eating late and getting up late. All these lead an individual to a pre-diabetic stage.”

Most doctors recommend a minimum of eight to nine hours of sleep. Also, sleep requirements change as you age, say doctors.

“While treating those with pre-diabetic conditions, sleep is one of the elements we look into. We tell people to get adequate rest so that their stress levels and cortisol hormones are not high. Obesity and stress hormones also cause blood pressure to shoot up, proving how all these aspects are interrelated,” Dr Mahesh adds.

Jesse Cook points out the relationship between lack of sleep and an increased risk of cardiovascular conditions. “Recently (2021), Korostostseva and colleagues published a review, ‘Sleep and Cardiovascular Risk,’ which presents an established understanding of heightened cardiovascular risks, such as hypertension, cardiac arrhythmias, automatic dysregulation and metabolic consequences associated with specific sleep disorders. Overall, sleep influences heart health directly and indirectly. A clear example of the direct effects can be seen from the work of Donga and colleagues in 2010, whereby a single night of partial sleep deprivation, induced insulin resistance in otherwise healthy persons. Yet, sleep health is also going to impact other domains of health, such as mental health and physical activity; that will in-turn indirectly affect heart health.”