How Does Sleep Effect Weight Loss?

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Brief Article Overview

• Chronic sleep deprivation can be defined as <6hours of quality sleep a night, most nights, which is a pervasive and prominent problem in modern 24h society (11).
• There is a large body of evidence that links chronic sleep deprivation to the development of several health dysfunctions such as cardiovascular disease, diabetes and hypertension.
• A lack of sleep is not only strongly associated with obesity, metabolic syndrome and elevated stress levels, but may perpetuate one another via feedback loops, developing a downward spiral that can be hard to break.
• Our 4 basic rules to help improve your sleep quality and quantity;

1. Keep it regular: Try to keep a consistent 8hour “window of opportunity” to sleep at regular times.
2. Take time to unwind: Take at least 30 minutes before bed, limit your screen time and adopt a routine that helps you unwind e.g: taking a bath, listening to calming music, meditation or reading.
3. Improve your sleeping environment: Keep your bedroom clean, tidy, cool and dark.
4. Limit nutritional sleep disrupters: Such as caffeine and alcohol.

Optimum vs Minimum

In our previous sleep article, we identified that a large percentage of the UK population is regularly getting less than 6 hours of sleep a night. In terms of sleep length, we find that there is a distinction to be made between optimum and minimum. The current research is pretty clear….6 hours of actual sleep a night (not just time in bed) is the minimum dosage before health and wellbeing start to decline. 

The classic recommendation “8 hours a night”, on the other hand, is regarded as the optimum amount of sleep for adults. This number has been derived from systematic reviews investigating correlations between sleep, health and mortality (10). This is proposed as the optimal sleep length to support physical and cognitive function.

Moving forward in this article then, we will define chronic sleep deprivation as regularly and consistently getting less than 6 hours of sleep per night.

Don’t get us wrong, we understand that life is to be lived. We all have different priorities we devote our time to such as social, family and work commitments. The occasional bad night’s sleep is not the end of the world (unless you’re driving a car or operating heavy machinery the next day!), but chronic sleep deprivation can be corrosive to one’s health. We argue, therefore, that sleep should be prioritised highly if the endeavour is to improve or optimise health and wellbeing.

Sleep and Stress

The Autonomic Nervous System (ANS) stems from the brain, down our spinal column and branches out to connect, control and innovate all bodily systems and functions. It is a largely unconscious network that acts in response to feedback from both internal and external environments. It’s a primitive system, and its main objective is to survive at all costs, even if those costs are detrimental to long term health and wellbeing. In other words, it prioritises immediate survival over longevity (which makes sense from an evolutionary perspective). The ANS is split into two distinct pathways;

1. Parasympathetic: dominant when the body is perceived to be safe and relaxed, initiating recovery, restorative and adaptive processes.
2. Sympathetic: dominant when the body is perceived to be under threat, stimulating a stress response, which primes the body for action. 

These pathways are always working together in a highly complex manner, but at any given time, one will be more dominant than the other depending on the brain’s perception of feedback from internal and external cues. Most of our waking hours are spent in a sympathetic dominant state. Sleep is the only truly parasympathetic dominant activity we regularly perform. Finding the balance between these pathways is crucial for optimal health and wellbeing.

When you don’t get enough sleep, your body will respond as if it were in a threatening environment. This is known as a sympathoadrenal response, which is initiated by the release of stress hormones from the Hypothalamus Pituitary Axis (HPA). This response increases alertness and primes the body for action. These processes are vital in temporary bouts but can be toxic to your health if left in a chronic state. 

The stress hormones of note here are that of glucocorticoids (including cortisol) and catecholamines (including epinephrine, which you may know as adrenaline). Adrenaline increases heart rate, elevates blood pressure, expands lung capacity, and sends blood to muscles, whilst cortisol shuttles sugar (glucose) into the bloodstream and suppresses digestive, immune, reproductive and growth processes. 

Remember these hormones, don’t cause stress, they occur in response to stress, which then initiates a cascade of physiological and psychological processes. 

Naturally, these hormone levels drop after the perceived threat has passed. When sleep deprivation is chronic, however, this sympathetic tone remains elevated which, in turn, can hinder the ability to fall asleep or sleep well.  Unfortunately, it’s quite easy to get stuck in a perpetual sleep deprivation /high-stress feedback loop, which can spiral out of control and may contribute to a plethora of health issues including obesity and metabolic syndrome. 

Sleep and Weight Gain

Sleep deprivation has been consistently and repeatedly linked with weight gain (1), obesity (2,3) and unfavourable metabolic responses and adaptations (4). The causal mechanisms behind this phenomenon are not clear and probably involve multiple interactions and variables, having said that, there have been a few proposals put forth by the scientific community. 

One popular mechanism involves hunger hormones, Leptin and Ghrelin. Leptin suppresses appetite and Ghrelin stimulates appetite. The onset of sleep causes the levels of Leptin to rise and Ghrelin to fall,  so you don’t feel hungry when you sleep (5). Chronic sleep deprivation disrupts this natural cycle, causing waking levels of Leptin to fall and Ghrelin to rise, signalling a state of pseudo-famine. This could, in part, explain the reason, people who are sleep deprived experience higher rates of hunger, cravings, snacking, the number of meals eaten per day and a preference for energy-rich foods. (6). 

Interestingly, eating in the absence of hunger also increases when sleep is restricted. Recent neuroimaging (fMRI) experiments show that insufficient sleep increases the brain’s pleasure response to food (known as a hedonic response) especially when said food is hyper-palatable, high in sugar, fat and calories (7,8). 

Decision making is also negatively affected by sleep deprivation. Another neuroimaging study found that short sleep alters functional connections between the prefrontal cortex and the brain’s reward- and emotion-processing centres, impairing so-called “executive functions” (9). As a result, we become hypersensitive to rewarding stimuli (such as tasty food), our emotional responses are heightened (causing increased cravings), and we are less able to make the difficult decision when it’s the right thing to do, all of which can contribute to increased caloric intake.

Other simple and fairly obvious mechanisms include the link between fatigue and reduced energy expenditure. In other words, the more tired you are, the less movement you’ll achieve during the day and the less likely you’ll be to exercise. 

Strategies For a Better Night’s Sleep

1. Keep a Regular Sleeping Pattern

We should aim to go to bed and wake up at the same time each day. People generally have a hard time adjusting to changes in sleep patterns. Unfortunately sleeping late on weekends doesn’t make up for poor sleep during the week. 

Strategy: 

• Because of our family/work commitments, our wake up time is usually routine. Use this regularity to reverse engineer your bedtime and stick to it.
• Give yourself a 30min time window to unwind, 15mins to fall asleep, an 8-hour opportunity to sleep and 15min to gradually wake up. For example: 

2. Set Aside Time to Unwind

This doesn’t mean sitting on the sofa binge-watching Netflix! This means entering a state which primes your mind and body for sleep. Set an alarm at least 30mins before you want to go to bed and establish a pre-bed routine.

The strategy: 

• Turn off the TV.
• Get away from your phone and laptop (this is a notoriously difficult one). 
• Turn the lights down. 
• Do something relaxing such as breathing, stretching, foam rolling, having a bath, meditating, reading a book, etc.

3. Improve Your Sleep Environment

The environment in which we sleep can have a profound effect on our ability to nod off. Here are some simple rules to follow in this regard to improve the odds of getting a good night’s sleep:

The Strategy:

• The darker the better – light is a stimulant, which your body is very sensitive to, even when our eyes are shut. Invest in thick blackout blinds, keep any light-emitting devices to a minimum and use a sleeping mask if necessary.
• Keep it cool – A gradual temperature drop is another cue your body uses to initiate its sleep mechanisms and sleep quality is much higher in moderately low temperatures. Set your thermostat to a cool, but comfortable 15-20ºC (60-67ºF) at least an hour before bedtime. For those without thermostats or air conditioning, you could invest in a special cooling sleep system (such as the ChiliPAD made by the Chilisleep company), or at least make sure your radiators are turned off at night and crack a window if necessary.
• Keep your bedroom clean and tidy – disorganisation and messiness often reflect in our thoughts, one way to help declutter our internal environments is by tidying up our immediate external environment.

OK so we have our regular sleeping patterns in place, we’ve established pre-bed routines to help us unwind and our sleep environments are cool, dark and tidy the next two recommendations are about two of the most common sleep disruptors we regularly consume; caffeine and alcohol.

4. Adopt a Caffeine Curfew

Now, in an ideal scenario, we wouldn’t need the aid of stimulants to feel awake, but coffee in the morning or before a workout isn’t the end of the world and may even be beneficial to our health and performance. 

It’s important to note, however, that caffeine has an average half-life of 5-6 hours (this does vary between individuals). This can mean that the caffeine from your after-dinner coffee/tea/caffeinated soda at 8pm could still be having a significant stimulatory effect until at least 2am! 

The Strategy: 

• This one’s simple, don’t consume caffeinated beverages beyond 4pm. 
• Replace with de-caffeinated alternatives if necessary. 

5. Skip the Nightcap 

Alcohol can have a detrimental effect on sleep quantity and quality. After a few glasses, or pints, or bottles(!) you may find that you can fall asleep fairly quickly, but experience multiple “mini-awakenings” during the night. This can be the reason you feel so tired and lethargic the next day, a big contributor to that dreaded hangover. 

According to the National Sleep Foundation, alcohol reduces the quality and quantity of your sleep in the following ways:

1. It activates different sleep rhythms simultaneously, which battle against each other, causing multiple disturbances. 
2. It blocks REM sleep.
3. It’s a diuretic, which means multiple trips to the bathroom! 

The idea of the nightcap is therefore paradoxical, and according to sleep expert Matthew Walker:

“Alcohol sedates you out of wakefulness, but it does not induce natural sleep” 

The strategy: 

• Try not to use alcohol as a means of distressing at the end of the day.
• Try to reduce regular alcohol consumption, staying teetotal for most nights of the week.
• Replace with non-alcoholic alternatives if necessary.
• Replace the routine of drinking with an alternative pre-bed routine previously mentioned, to help you unwind. 

Summary

We hope our sleep articles (part 1 and 2), have highlighted the importance of getting good quality, regular sleep of sufficient quantity. The intent of these articles was not to simply tell you to get more sleep but to investigate the reasons why sleep is important, the causal mechanisms between sleep and some select health outcomes, and then to suggest actionable steps towards improving your sleep hygiene. 

These suggestions are a good start, but remember that it’s ultimately down to you when it comes to taking your health into your own hands! The evidence suggests that good sleep is non-negotiable, so why not do some experimenting and investigating into your own sleep and find what works for you! 

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Disclosure: This is article is not to be used as medical advice. If you are currently experiencing physical or mental health issues, please seek professional advice from a fully qualified Nutritionist, GP or Physiotherapist.

References

1. Short Sleep Duration and Weight Gain: A Systematic Review. (2008) Patel, S. and Hu, F. 
2. Meta-Analysis of Short Sleep Duration and Obesity in Children and Adults. (2008) Cappuccio, F., Taggart, F., Kandala, N., Currie, A., Peile, E., Stranges, S. and Miller, M.
3. The link between short sleep duration and obesity: we should recommend more sleep to prevent obesity. (2006) Taheri, S.
4. Short Sleep Duration Is Associated with Reduced Leptin, Elevated Ghrelin, and Increased Body Mass Index. (2004) Taheri, S., Lin, L., Austin, D., Young, T. and Mignot, E. 
5. A single night of sleep deprivation increases ghrelin levels and feelings of hunger in normal-weight healthy men. (2004) SCHMID, S., HALLSCHMID, M., JAUCH-CHARA, K., BORN, J. and SCHULTES, B. 
6. Eating patterns and nutritional characteristics associated with sleep duration. (2011). Kim, S., DeRoo, L. and Sandler, D. 
7. Acute Sleep Deprivation Enhances the Brain’s Response to Hedonic Food Stimuli: An fMRI Study. (2012) Benedict, C., Brooks, S., O’Daly, O., Almèn, M., Morell, A., Åberg, K., Gingnell, M., Schultes, B., Hallschmid, M., Broman, J., Larsson, E. and Schiöth, H. 
8. Sleep Deprivation Selectively Upregulates an Amygdala–Hypothalamic Circuit Involved in Food Reward. (2019) Rihm, J., Menz, M., Schultz, H., Bruder, L., Schilbach, L., Schmid, S. and Peters, J. 
9. Sleep deprivation: Impact on cognitive performance. (2007) Paula Alhola, P.
10. Sleep Duration and All-Cause Mortality: A Systematic Review and Meta-Analysis of Prospective Studies. (2010)Cappuccio, F., D’Elia, L., Strazzullo, P. and Miller, M.
11. The Global Problem of Insufficient Sleep and Its Serious Public Health Implications. (2018) Chattu VK, Manzar MD, Kumary S, Burman D, Spence DW, Pandi-Perumal SR. Healthcare (Basel);7(1):1. Published 2018 Dec 20. doi:10.3390/healthcare7010001