Sleep is a very important part of life but in the fast-paced world it is often pushed back or neglected due to social life, binge watching, working, and late-night gossip. Sleep deprivation is close to becoming a global pandemic. It is often overlooked on how it impacts our health negatively. 

Sleep is not only helpful for resting but also for healing, memory restoration, and preparing the body for the next day. It also helps in the function of the body like developmental repairment, cognition, memory, immune function and psychological state. 

The science behind the impact of food intake, time of eating, how it affects our body clock and the sleep wake cycle is called chrono-nutrition. Either one of them is poor and it affects our circadian rhythm. 

Do you crave sugary snacks or oily snacks while you stay awake late at night? Poor dietary choices are made late at night which disrupts the sleep and the eating behaviour. 

In this blog you can understand the relationship between poor sleep, poor diet and its impact on health. 

Circadian rhythm 

Circadian rhythm is the natural cycle of physical, mental and behaviour changes that happens in a 24 hour cycle. 

Most recognised circadian rhythm is the sleep-wake cycle. Body’s circadian rhythm plays a role in how the brain and body respond to darkness. 

In a person with healthy sleep hygiene, the body’s biological clock instructs the cells to slow down in the night. The hormone melatonin responsible for inducing sleep is produced during the night and its production increases around 2-4 am and in the morning the levels go down. 

Our circadian rhythm is disrupted due many reasons like having a bad sleeping habits like:

• Staying out very late at night and waking up early in the morning. 
  
  
• Not having a proper sleep schedule.
  
  
• Eating or drinking very late at night.
  
  
• Having a caffeine rich beverage before going to bed.
  
  
• Watching a late night movie, series or using a mobile phone.
  
  
• Not having a proper sleep environment. 
  
  
• Working late shifts or night shifts.
  
  
• Travelling often.
  
  
• Having different colour lights in the room. The light intensity affects the circadian rhythm. 
  
  

Relationship between sleep, diet and hormones

The relationship between poor sleep and poor diet can create a vicious cycle.

1. Leptin and ghrelin hormones

Hormones that regulate hunger and satiety are ghrelin and leptin. Ghrelin is called the hunger hormone which signals the brain when you have not eaten for a while and leptin hormone signals the brain and makes you feel satiated. 

When sleep is disturbed, the body manipulates the brain into thinking that the body needs energy and releases more ghrelin hormone making you feel hungry late at night. We often make poor choices and have high-calorie food and sometimes we binge eat while watching our favourite movie or series. Late night snacks and binge eating contributes to weight gain and metabolic issues. 

In a person with good sleep hygiene, the leptin levels are high during the night and also signals the brain to feel satiated and save energy for other body functions. But in sleep deprivation the levels of ghrelin are high and leptin is low. 

Leptin levels fall only in chronic sleep deprivation. Levels of leptin do not fall low in acute sleep deprivation (one day of poor sleep) and does cause the ghrelin level to rise.

2. Insulin resistance

Insufficient sleep causes the body to release stress hormones. These stress hormones increase the insulin resistance in the body, they act on pancreatic beta cells and disrupt the body’s response to insulin. In stressful situations the body ensures that there is enough energy available. When the stress hormone levels rise, the level of insulin falls low. The rise in stress hormones reduces the insulin sensitivity in the body and glucose which is stored as glycogen in the liver is released in the blood.
 

3. Increased stress hormones

In disturbed sleep or sleep deprived individuals, the body’s stress response system is triggered. This causes the body to release stress hormones like cortisol and adrenaline. Prolonged high levels of cortisol increases body weight and increases the risk of cardiovascular diseases. Cortisol levels are increased when an individual sleeps less than 5 hours a day.
 

Poor sleep and poor diet 

In sleep deprivation, the prefrontal cortex which is responsible for decision making and self-control becomes less effective and reduces function. The amygdala (a part of the brain which is important in making decisions) is activated in sleep deprivation. These altered neuro changes are linked with increased appetite and lead to poor decision making. This causes a shift in the dietary choice and the shift is towards the high calorie food items. 

A study was conducted to understand the science behind why we eat junk food at night. On analysing the brain fMRI showed that in the sleep deprived individuals the connection between insular cortex and piriform cortex is reduced and there is an increase in one of the two endocannabinoid – 2-OG is activated. The role of the piriform cortex is to send information to the insular cortex about the food intake, smell and how much food is in the stomach. When connection between the piriform cortex and insular cortex is poor, the individual eats large amounts of high calorie food to satisfy hunger. 

Poor sleep increases the stress hormones that affect the psychological and emotional state which lead to emotional eating and turn to comfort food to cope with feelings. Lack of sleep can make it difficult to cope with stress and emotional eating, and makes you crave for more food. This creates a cycle of poor sleep, increased stress and food craving.

Poor sleep and metabolic health

Chronic sleep deprivation affects metabolic health and increases the risk of obesity, hypertension and diabetes, depression, heart attack, stroke and more. 

1. Poor sleep and weight gain

Sleeping less than 7-8 hours a day increases the dose-response relationship between sleep and body weight. insufficient sleep leads to increased ghrelin hormone and low levels of leptin hormone. This increase in ghrelin hormone increases the appetite and you tend to eat more. Stress hormones are elevated in the individuals with sleep deprivation, this also increases risk of emotional eating. This explains the relationship between sleep deprivation and obesity.
 

2. Poor sleep and diabetes

Chronic sleeplessness increases impaired glucose tolerance. Frequent fluctuation of blood glucose levels, stress, and emotional eating increases the chance of diabetes. A study conducted by the Sleep Heart Health study reported that 5 hours of sleep or less increases the risk of having diabetes 2.5 times more. 

3. Poor sleep and hypertension

In individuals with good sleep hygiene, the blood pressure drops 10-20% in the night, this is called nocturnal dipping. In sleep deprived individuals the blood pressure does not drop, this non-dipping is linked to increase in the risk of stroke, heart attack, kidney diseases and poor blood flow to the brain. 

Studies found that nocturnal blood pressure is linked to overall blood pressure and increases the risk of heart problems. Individuals who are working in high stress jobs have high blood pressure and poor sleep which increases the risk of hypertension.
 

4. Poor sleep and coronary heart disease

Poor sleep increases chronic inflammation. Coronary heart disease or coronary artery disease is when plaque (excess fat form plaques) get built up in the arteries, this narrows and hardens the arteries causing atherosclerosis. The heart does not get enough oxygen and blood. This plaque formed due to inflammation. 

5. Poor sleep and heart failure

Poor sleep increases weight and causes other health problems like obstructive sleep apnoea (OSA). In OSA, the throat blocks the airway. Brain signals the throat to relax to open the airway. This occurs multiple times at night, this causes the brain to release stress hormones, these stress hormones, increases the blood pressure and heart rate. Chronic sleep deprivation increases stress and overtime it weakens the heart.
 

6. Poor sleep and heart attack

Sleep deprivation influences poor sleep, stress and inflammation, this can raise the risk of cardiovascular disease. Inflammation caused due to poor sleep increases the rise of heart attack. When the blood flow is blocked to the heart, it causes heart attack. Heart rate and blood pressure raises the risk of sleeplessness. It also increases cardiac stress which may induce heart attack.
 

7. Poor sleep and stroke

Stroke is caused when the flow of blood to the brain is stopped. This causes the cell in the brain to die due to lack of oxygen. Insufficient sleep increases the blood pressure, blockages by forming plaque. Increase in blood pressure is a risk factor for stroke.

8. Poor sleep and mood

In adults chronic sleep deprivation experience severe mental distress, depression, and anxiety. This often leads to behaviour problems and alcohol use for coping. In severe cases people tend to attempt suicide. 

Yes, poor sleep does lead to poor diet. From the above we understand sleep does not only relaxes the body and mind but is also very important for many body functions and also prevents metabolic conditions. 

An average human needs 7-8 hours of sleep. Women need more sleep compared to men because hormones are associated with circadian rhythm and women experience various hormonal changes every month that can impact their circadian rhythm. Studies show that women are 40% more prone to insomnia, anxiety and depression. 

Tips to follow for good sleep hygiene 

• Treat sleep as your first priority.
• Plan and maintain a sleep schedule.
• Switch off all your electronics 2 hours before sleeping.
• Exercise daily. 
• Don’t drink any caffeinated beverages 2 hours before.
• Set your bedroom temperature optimum for sleep.
• Don’t use any bright lights in the bedroom. 
  
  

Kripa N,
Senior Clinical Dietitian, Simplyweight