Obesity, defined as a body mass index (BMI) of 30 or above, increases the risk of a multitude of chronic health conditions including Type 2 diabetes, hypertension, coronary heart disease, endometrial, breast, and colon cancers, dyslipidemia (high cholesterol and triglycerides, stroke, liver and gallbladder disease, sleep apnea and respiratory problems, and osteoarthritis of the knee. It is now understood that most people do not gain large amounts of weight at once – rather, people usually gain a few pounds a year until they find themselves facing a cumulative substantial weight gain many years down the road. This is exacerbated by the unfortunate fact that metabolism slows as a result of the aging process, leading to increased difficulty in weight loss as one gets older. In fact, in order to maintain the same weight as we age requires reduced calorie intake/increased physical activity. For this reason, it is always better to circumvent weight gain in the first place.

Sleep fulfills the following three major functions:

• It serves as the energy restoration period from daytime activities
• It affords bodily protection at night when sensory capacities are down-regulated
• It allows the brain to consolidate experiences and memories for learning

Geoff Colvin, in his book Talent is Overrated, writes about a study of violinists at an elite music school which tried to answer the question of why some musicians are better than others. The study looked at three different groups: the very best students, the good students, and students in a separate program stream that had lower admission standards. Although Colvin’s book actually examines the concept of deliberate practice in success, not sleep, it was interesting to note that the top group of violinists slept more than the other two groups.

In terms of obesity, other contributing factors have been identified. Chronic sleep deprivation, exceedingly common in today’s Western world, has been recognized as one of the causes of obesity. It is also possible that obesity itself may impact on the quality and duration of sleep. Most adults require 7-8 hours of sleep, and chronic sleep debt is defined as having more than 4 but less than 7 hours per night. I am not speaking of acute sleep deprivation, which happens infrequently during long travels, scrambling to finish a piece of work last minute, or waking up with a sick child. Chronic sleep is exactly that: long periods of time in an individual’s life when insufficient sleep is experienced.

The three major processes linking chronic sleep restriction to obesity are metabolic and neuroendocrine function, glucose regulation and waking behaviour.

Metabolic and Neuroendocrine Function

It has been found that chronic sleep restriction elevates the sympathetic nervous system, increasing evening cortisol production. This in turn can increase food intake and the accumulation of abdominal fat. In addition, sleep debt is associated with lower levels of leptin secretion. Leptin is secreted from fat cells and transmits energy balance messages to the hypothalamus (the brain centre for hunger). As leptin levels decrease, the hypothalamus interprets the message that the fat cells need more food and directs the body to eat more. Moreover, insufficient sleep leads to a significant increase in ghrelin, a hunger hormone produced and secreted from the stomach. Higher than normal circulating ghrelin levels stimulate hunger and food intake.

Glucose Regulation Processes

Chronic sleep deprivation is connected to impaired glucose metabolism, leading to a strong association between sleep debt and diabetes. Impaired glucose regulation is often coupled with weight gain – glucose plays an important role in regulating appetite. When glucose metabolism is compromised, which occurs with sleep debt, glucose utilization in parts of the brain becomes impaired. This promotes the hunger response.

Waking Behavior

This is simple – more time awake means more opportunities to eat. Due to the ubiquity of technology people often find themselves awake later than they would have been in years past. Moreover, many people find themselves tired during the day precisely because of inadequate sleep, and compensate for this by consuming caffeinated beverages to stay alert. This creates a vicious cycle in which it then becomes difficult to fall asleep at night.

References:

Colvin, G. (2008). Talent is Overrated. Penguin: USA.

Kravitz, L. (2010). Chronic sleep restriction is a risk factor for obesity. IDEA Fitness Journal, pp. 21-23.

Exercise Specialist Recommendations:

• Set a regular bedtime and stick to it.
• Do not consume caffeine after 1pm.
• Avoid exposure to bright light, television, computer, or tablets one hour before bedtime.
• Avoid stimulating conversations, either in person or by phone, one hour before bedtime.
• Do not do work one hour before bedtime.
• Limit naps to 30 minutes, and try to take them earlier in the day.
• Exercise in the mid or late afternoon – this has been shown to have positive effect on sleep quality.
• Do not smoke or use nicotine before bed, as nicotine keeps many people awake.
• Sleep in a very dark room.
• Block out noise with earplugs.
• Keep ambient temperature cool.
• Avoid drinking lots of fluids after dinner.
• Establish a relaxing bedtime routine that might include reading, drinking herbal tea, quiet time with your partner if applicable, and mediation or simple deep breathing.

Changing behaviour of any sort is very hard to do – but diligent adherence to the above set of recommendations will enable the chronically sleep-deprived to learn what it feels like to be truly well-rested. Once this experienced, there is no turning back.