Sick and Tired of Being Overweight? Get More Sleep!

Sleep-Deprived? Not me!

Sleep-Deprived? Not me!

Sleep? Not me!

The US is a country of sleep-deprived people. Data from the National Health Interview Survey revealed that nearly 30% of adults reported an average of 6 or fewer hours of sleep per day in 2005-2007 (as opposed to the recommended 8 hours). The US is also a nation of people who are increasingly overweight or obese. Might the two be connected?

Sleep is more than rest

Sleep is downtime. But, more importantly, it is also a time for repair of neurons. Good sleep helps immunity, and is important for learning, forming memories, and maintaining a healthy immune system.

An increasing number of health problems have been linked to poor or insufficient sleep, including links between poor sleep and weight problems.

A large body of research suggests that sleep-deprivation can lead to obesity. A previous article from our archives outlines many of the mechanisms involved, and it can be reviewed here …

Reward, addiction, food, and the brain

Researchers have started focusing on the nature and mechanism of reward and the involvement of specific brain centers in certain behavior patterns, including food intake, and even drug addiction.

The mesolimbic dopamine system is the most important reward pathway in the brain, leading to the transfer of dopamine from one part of the brain to another. This system regulates the formation of habits.

The Triune brain of mammals: 3 in 1!

brain-147148_1280Proposed by Paul MacLean, this is a simplified, some say oversimplified, way of looking at the brain from the evolutionary point of view. It means three brains in one. There is the oldest part of the brain, or reptilian brain, which is involved in the processes necessary for survival, such as breathing, heart rate, balance, body temperature, and the like. It is basically the brainstem.

The limbic system, or the paleomammalian brain, is the second oldest part of the brain. Limbus refers to a border. This limbic system is the collective name given to a set of structures surrounding the limit between the brainstem and the cerebral hemispheres. This is where the cerebral cortex meets the structures beneath it.

Traditionally, the limbic system is felt to include the hypothalamus, the amygdala, the hippocampus, and other surrounding areas. It is responsible for emotions, memories, and value judgments.

The mesolimbic system is the more central part of the limbic system. It connects the ventral tegmental area in the midbrain to the nucleus accumbens. Functioning as a reward pathway, this system is involved significantly in most known forms of addiction.

The neocortex is the outer part of the brain and is mostly made up of two large cerebral hemispheres, which deal with language, consciousness, abstract thought, imagination, stimulus analysis, and motor control. It is the youngest part of the brain.

What about the endocannabinoid system?

This is triggered in people who smoke marijuana.

This system is also implicated in the reward mechanisms involving the brain and its pathways.  It mediates the psychological effects of cannabis, and is therefore also called the body’s own cannabinoid system. It is made up of lipids (or fats) and their receptors.

There are two main endocannabinoid receptors, called CB1and CB2. The main lipids which are part of this system, and which act on the receptors already mentioned, are 2-AG and CBD.

This system appears to be involved in reward-driven or pleasure eating.

A recent study out of the University of Chicago found that people who were sleep-deprived had a greater activation of their endocannabinoid system.

People who had a full night’s sleep, in this study, ate 600 calories in early evening snacks. However, people who were sleep-deprived consumed almost 1000 calories in such snacks, and ate twice as much fat.


Consuming 400 extra calories a day regularly can lead to up to 40 lbs of weight gain in a year!

2-AG levels

This endocannabinoid can be measured in the bloodstream. Average levels of this lipid were similar in the people who had shorter-duration sleep (4.5 hours) versus normal-duration sleep (8.5 hours) in the Chicago study. However, the peak levels were higher in sleep-deprived people, and this peak occurred later in the day. Interestingly, the sleep-deprived individuals felt hungrier at the time of the peak 2-AG levels, and reported a stronger desire to eat at those times.

So what’s the link?

Several studies have investigated the links between sleep, food intake, and obesity.

There is evidence that sleep deprivation leads to an increase in the blood levels of ghrelin, a hormone which causes an increase in hunger, and a reduction in leptin, which suppresses hunger. The net effect is an increase in food intake in people who do not get sufficient sleep.

It can be argued that if you do not get enough sleep, you are obviously awake for longer, and thus your energy expenditure will be higher, just because you are awake, and probably engaged in some activity or the other. However, the increase in food intake in sleep-deprived people over-rides their excess energy expenditure. Thus the weight gain we see with sleep deprivation.

BMR and sleep deprivation

A study performed by researchers at the University of Pennsylvania School of Medicine in 2015 revealed that people who were sleep deprived for five days had a lower Basal Metabolic Rate (BMR) in the morning compared with their BMR after a night of normal sleep. Extrapolating this, the researchers found that people who were sleep deprived burned 42 calories less the next morning, compared with people who had a normal duration of sleep.

Food type




Sleep deprived individuals tend to have a greater craving for salty food, followed by sweet foods. This is also likely to contribute to their weight gain. Additionally, sleep deprivation seems to lead people to eat more snacks, rather than larger meals.

Diet and sleep deprivation

At least one study has found that sleep deprived people who go on a diet end up losing more lean body mass rather than fat mass.

Food and sleep quality

How well you sleep affects what you eat, and how much. But, interestingly, what you eat during the day can also affect how well you sleep that night.

People who eat more sugar during the day tend to wake up more in the middle of the night. Higher fiber consumption during the day is associated with more slow-wave sleep, which is deep sleep, felt to be important for new memories.

By contrast, a higher intake of saturated fat during the day is associated with less slow-wave sleep.


  • Sleep and body weight are intricately related.
  • There is a clear relationship between sleep deprivation and weight gain.
  • The mechanisms are not entirely clear, but appear to be related to changes in ghrelin and leptin levels, as well as stimulation of the endocannabinoid system.
  • The endocannabinoid system is a reward system involving the brain, and appears to encourage snacking and higher caloric intake.
  • Sleep deprivation tends to promote intake of salty and sugary foods.
  • Food choices during the day (fiber, sugar, saturated fat) can alter sleep quality at night.
  • Sleep deprivation is also associated with many other significant health problems.
  • Many Americans (and likely those in other parts of the world as well) are not getting the recommended amount of sleep. Healthcare providers need to make a concerted effort to promote healthy and adequate sleep in the population at large.

Sleep Deprivation Makes Us Obese and Inattentive: Can We Make Up Sleep Debt?

Sleep is vastly undervalued. We like to “burn the midnight oil,” and then brag about it. For medical interns, working long hours with little sleep is almost a rite of passage. World leaders and corporate titans take pride in declaring their ability to function round the clock. They are all sadly mistaken.

Human adults need 7 to 8 hours of sleep every night. The brain, the rest of the body, our metabolism, our mood: All of these are heavily dependent on adequate sleep to function properly.

Sleep and obesity

The links between sleep and body weight have only recently received focused research attention. There is little doubt now that sustained sleep deprivation predisposes a person to obesity by affecting both appetite and activity.

Sleep and hunger hormones

Leptin and ghrelin are hormones which regulate hunger, satiety and appetite. Leptin is the satiety hormone. It is secreted by fat cells, and sends a signal to the brain that you are full. The brain then suppresses your appetite, and hopefully you stop eating at that point. But sleep deprivation interferes with this mechanism. It has been shown that reducing sleep time to 4 hours a night for 6 days significantly reduces the blood levels of leptin, so you do not get the signal to cut down on food intake. Appetite is increased, even though the body may not need extra calories.

Ghrelin, by contrast, is the ‘hunger hormone’ produced by the stomach. It increases appetite. Sleep reduction to just 4 hours a night for 2 days causes a rise in ghrelin levels, and an increase in appetite.

Thus loss of adequate sleep time interferes with the ability of the body to regulate appetite based on its caloric needs.

Sleep and activity

Even one night of partial sleep deprivation has been shown to be potentially harmful. Otherwise healthy people subjected to sleep loss have reduced activity levels the following day. Sleeping for fewer than 6 hours a night on a regular basis leads to significantly lower activity levels.

So loss of sleep causes increased caloric intake and reduced energy expenditure. This combination explains the link between sleep deprivation and obesity.

Because of the factors mentioned above, sleep deprivation interferes with the ability of a low calorie diet to successfully induce weight loss.

Clearly, if you want to lose weight and keep it off long-term, your odds will increase if you sleep regularly for 8 hours a night.

Sleep and cognition

Research clearly reflects that sleep is important for memory, focus, attention, and cognition. Sleep deprivation adversely affects all of these important skills.

But life is hectic. Who has time to sleep?

It is easy to give advice about sleep, but modern life intervenes. So is all lost? Not necessarily.

It is important to follow certain principles of sleep hygiene to make the best of the hours of sleep you do get. Try to keep your sleeping area dark, slightly on the cooler side, and free from distractions such as TV, computers, cell phones, etc.

You should try and maintain as regular a schedule of sleeping as possible, with fairly fixed hours of going to bed and waking up. Obviously, this is easier said than done, but it is a goal worth striving for.

Alcohol and caffeine can interfere with sleep, and one should avoid their use for several hours before bedtime.

People who exercise regularly improve their sleep quality. However, do not exercise for about 3 hours before you plan to go to bed.

Can you make up for lost sleep?

Well, napping has been tried. This can improve your mood and also alertness level in the short term. Naps can improve performance, but it is unlikely that a nap will make up for poor quality sleep, or for long-term sleep deprivation.

It is also unclear whether napping can reverse the metabolic effects of sleep deprivation, particularly the effects on weight gain.

Also, if you do nap, it appears that 10 minutes produce the most benefit, according to a study in Sleep. Napping for more than 30 minutes may end up making you feel groggy.

There is also a suggestion that long naps can interfere with night-time sleep, affecting both its duration and quality. The same problem can occur if you nap late in the afternoon or evening, closer to bed time.

Pay off sleep debt?

It has been suggested that you can make up for an accumulated sleep deficit by sleeping longer on weekends, or during a vacation when you can set your own schedule, and get extra sleep each night, waking up naturally in the mornings without an alarm.

Research shows that some effects of sleep debt, such as daytime sleepiness, can be mitigated by this method. However, impaired attention levels caused by sleep deprivation may not improve with catch-up sleep.

There is a recent study showing that we might not be able to counter the effects of chronic sleep deprivation. This is a study in mice, but it should raise concern. Penn Medicine researchers published a study in The Journal of Neuroscience in March 2014, showing the effects of sleep deprivation in mice. They found that after short-term sleep deprivation, mice brains were able to change the levels of an important protein to protect brain cells from injury.

However, if the sleep deprivation was prolonged, this protective response did not kick in, and mice brain cells started to die. The locus coeruleus is a brain region important for alertness and cognition. With long-term sleep loss, mice lost 25% of the nerve cells in this brain region. And, as they say, death is permanent.

So get enough sleep, starting tonight. Your brain will thank you, and your body will get lighter.






Let There Be Light–Or Not!

Daytime is bright. The night is supposed to be dark. We work during the day, and we should sleep at night. These are fairly simple concepts around which the human body was designed. Our hormones and our health depend on these principles.

Let there be sunshine

We need the sun and its light, all 32,000 to 100,000 lux of it (on a bright, sunny day). Even on an overcast day, the sun grants us 10,000 lux. Without sunshine, we would be miserable, or maybe not exist at all. We have all heard of Seasonal Affective Disorder (SAD), a type of depression suspected to result from not enough hours of sunlight.

So what is a lux? A lumen?

A lumen is, broadly speaking, the “quantity” of visible light that a source emits. A one watt lamp radiates approximately 683 lumens.

A lux is a measure of the intensity of illumination over a surface.  One lux is one lumen of light spread over one square meter.

Silent night, dark night

The night is supposed to be dark.

How dark? If there is an overcast sky with no moon and only the light of stars, we have 0.0001 lux. If there is a full moon, and the sky is clear, we get 0.27 lux. By way of comparison, street lights are at 320 lux and homes at 80 lux.

So what’s the problem?

We have a biological clock which functions in 24 hour cycles. The rhythms of this clock are called circadian rhythms (circa=about, dies=day), which are affected by periods of light and darkness.

This clock is located in a part of the hypothalamus region of the brain, an area called the suprachiasmatic nucleus. This biological clock sets times for us to fall asleep and to wake up. It also controls the release of hormones by our glands into our bloodstream. The ones we are most concerned about are cortisol and melatonin.

Light at night: bad!

Artificial light exposure at night causes problems with cortisol and melatonin secretion, which affects our health significantly.


This is a very important hormone produced by the adrenal glands. Normally, cortisol levels are higher during the day than at night. But exposure to artificial light at night alters the biological clock, and the rhythm of cortisol levels. This is suspected of having an effect on the quality and duration of sleep, and also on appetite and glucose/fat metabolism.

Cortisol levels are affected by both blue (short wavelength) and red (long wavelength) light.


This is a hormone produced by the pineal gland in the brain. How much of it the body produces depends on how dark it is at night and how much light we were exposed to the previous day.

Melatonin production by the body drops significantly if we are exposed to artificial light between sunset and our going to sleep. Blue light has more of an effect on this than red light. This causes problems with sleep, blood pressure levels, temperature regulation, and also blood sugar levels.

There is also a suggestion that exposure to artificial light at night (and the resulting low melatonin levels) may be associated with an increased risk of breast and prostate cancer.

Low melatonin levels may also be implicated in premature aging and depressed immunity.

Blue light may be helpful during the day, because it can improve mood, attention and reaction times. But at night, this short wavelength light causes problems. Compared to the light of standard bulbs, blue light is five times more powerful in reducing melatonin production.

Sources of blue light

LED TVs, digital clocks, light bulbs, laptops, monitor screens, smartphones, tablets and other similar electronic gadgets emit short-wavelength blue light which reduces melatonin levels.

So what to do?

  • Keep your bedroom pitch dark at night.
  • Turn off all electronic gadgets which emit light, especially blue light, two to three hours before bed time.
  • Use a dim red light, if a night light has to be used. This causes the least suppression of melatonin levels, and the least interference with our biological clocks.
  • Avoid watching TV or working on the computer just before going to bed.

In brief, don’t just curse the darkness: embrace it!

Sleep and its ten health benefits

“Sleep that knits up the ravell’d sleeve of care, the death of each day’s life, sore labour’s bath, balm of hurt minds, great nature’s second course, chief nourisher in life’s feast.”

-Macbeth, Act II, Sc. ii

As usual, Shakespeare had it right.

Ernest Hemingway also was on the right track when he said, “I love sleep. My life has a tendency to fall apart when I am awake.”

Modern research has added greatly to our understanding of sleep since the days of Hemingway. We now know much more about what sleep is, and how it helps us.

What happens during sleep?

The brain is quite active when we are asleep. Sleep is not just an opportunity for the brain to shut down. A lot of very important functions are performed by our brains while we sleep. Without this, we would not remain healthy for long.

How do we fall asleep?

A lot of research is going on in this area.

There is a school of thought that says that a chemical called adenosine builds up in our bodies during the day. Once it reaches a certain level, we start feeling drowsy, and eventually fall asleep.

The cells in the brain also produce chemicals. Some of these, such as serotonin and norepinephrine, keep us awake. It is felt that these signals for wakefulness are switched off by cells at the base of our brains at night, allowing us to sleep.

Another chemical which regulates sleep is a hormone called melatonin. This is produced by the pineal gland in our bodies. Its levels are reduced by bright light. At night, the levels of melatonin in our blood rise, and we drift off toward sleep.

How much sleep do we need?

Most adults need between 7-8 hours of sleep. Children and adolescents need more. After adulthood, sleep requirements do not change. Even elderly people need 7-8 hours of sleep.

What are the types of sleep?

Sleep is basically of two types: REM, or rapid eye movement sleep, and non-REM sleep.

Non-REM sleep has 4 stages, I-IV. Stage I is light sleep and Stages III & IV are deep sleep. In the first stage, our eyes move slowly and the activity of our muscles slows down. In the second stage, the eyes stop moving, and brain waves slow down. In the third stage, very slow brain waves are produced, called delta waves. Stage four is a deeper sleep than stage three.

REM sleep is characterized by a rise in heart rate and blood pressure, and, of course, rapid eye movements. The muscles of the arms and legs are temporarily paralyzed (presumably so people do not act out their dreams) and breathing is shallow, fast and irregular. This is the time when intense dreams occur.

Benefits of sleep

  • Memory

Research done at the New York University School of Medicine and Peking University Shenzhen Graduate School has shown that the sleeping brain creates more connections between nerve cells, leading to memory formation. This happens during deep or slow-wave sleep, when the brain replays activity from earlier in the day.

So if a student wants to retain stuff for a long time, he or she would be better off studying and then getting a good night’s sleep. This improves learning.images

  • Housekeeping/Cleaning

Waste materials and toxins build up in the brain in the waking state. The brain has a cleaning system to flush this out: the glymphatic system. This system is ten times more active during sleep, according to recent studies.

  • Problem solving

New, creative ways to solve problems are promoted by Rapid Eye Movement (REM) sleep, according to a study by the University of California, San Diego School of Medicine researchers. They believe that there are changes in chemicals produced in the brain during REM sleep, which stimulate the formation of “associative networks.” This apparently allows the brain to take ideas not related to each other, and try to make new connections between them.

  • Reflexes and focus

Adequate sleep improves your reaction time and reflexes. This is particularly important when you are driving, since slow reactions can lead to an accident.

People who have slept well are also able to focus better on the task at hand.images (2)

  • Growth

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The body releases more growth hormone during deep sleep (both REM and non-REM). This hormone obviously affects growth in children. It also contributes to muscle mass and cellular repair in children as well as adults.

  • Sex hormones

Sleep has an effect on the release of sex hormones, which are important for puberty and fertility.

  • Mood

Lack of sleep affects your mood and inter-personal reactions. It increases the risk of developing depression.

  • Immunity and infections

Certain proteins called cytokines help the body’s immune system to fight infections. The body makes more of these proteins during sleep.

Studies also show that vaccinations against influenza (and possibly other illnesses) work better to protect people who are well-rested.

  • Appetite and weight

Sleep strongly affects how the body uses energy. Production of leptin (a hormone which suppresses appetite) increases during sleep. Simultaneously, the production of ghrelin (a hormones which increases appetite) goes down.

These changes affect body weight, and sleep-deprived people are at risk of obesity.

In fact, there is some data showing that otherwise healthy people who are sleep deprived  can show signs of a diabetic-like condition.

  • Heart disease

Lack of sleep can also increase the risk of cardiovascular diseases.


Sleep affects almost every tissue in the body.

Make sure you get enough.

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