By Dr David Lee, BSc PhD CertEd AFBPsS CPsychol CSci, Clinical Director at Sleep Unlimited Ltd. September 2026.
Introduction
The weight loss industry is worth many billions, with a major focus on exercise regimes and eating well. Gyms are ubiquitous and our fascination with nutrition can be measured in the sheer numbers of celebrity chefs, cooking programmes and the huge global sales of cookbooks every year. Little attention, however, is paid to that ‘third pillar’ of health, that of achieving good quality sleep.
The exercise/nutrition/sleep triumvirate is well spoken about, but in reality, good quality sleep is the foundation stone upon which we build everything, including those pillars of exercise and nutrition. It doesn’t matter what you eat, or how much exercise you get, if you are not sleeping well, then everything else fails. Poor sleep has well established links with detriments in performance, behaviour, quality of life and contributes to a vast array of health conditions.
This article will detail the impact poor sleep has on our metabolism and the regulation of appetite, explaining why people with chronically disturbed sleep will very often struggle with managing their body weight, and then go on to describe some practical, evidence-based solutions to overcome both of these highly pervasive issues.
The impact of sleep deprivation on the human metabolism
Sleep deprivation either partial (and especially total) has myriad consequences on our metabolic as well as our psychological performance. We have good data that shows a significant link between sleep deprivation (both partial and total) and the development of Type II diabetes, obesity, and cardiovascular disease (Nedeltcheva & Scheer, 2014).
The development of these conditions has implicated inefficient glucose metabolism and insulin production with respect to Type II diabetes (Donga et al., 2010) and the hormones leptin and ghrelin with regard to obesity. Interestingly studies have found that partial sleep restriction impacts negatively on the balance of these hormones in both adults and children (Aldabal & Bahammam, 2011).
For the purposes of this article we will focus on two of the most important hormones involved in glucose metabolism and appetite regulation as these have a primary impact on hunger, satiety and bodyweight: the hormones leptin and ghrelin.
Leptin supresses appetite, making us feel sated, full-up and satisfied. Conversely, ghrelin stimulates appetite making us feel hungry and causes behavioural change to seek out food. Under conditions of sleep deprivation leptin levels decrease and ghrelin levels increase. So, we feel more hungry, less satisfied and more likely to seek out food when we are tired (Skoracka et al., 2025).
From an evolutionary biological perspective this makes a lot of sense and is ‘life preserving.’ Areas of our brainstem identify tiredness and a lack of sleep, instinctively, this is then interpreted as the eco-system placing us in a threatening situation: “for some reason I’m not sleeping, there must be some threat preventing me from sleeping, so, move to a place of safety and get some sleep.”
In order to encourage this ‘move to a place of safety,’ brainstem areas increase ghrelin and reduce leptin levels: “seek out energy rich foods (sugar and carbohydrates) to provide me with the energy I need to get to a place of safety.”
This is experienced at an emotional level, rational higher cortical functions e.g.: “I’m on a diet right now, I’m only eating small portions of healthy foods,” are completely overwhelmed by the survival strategy implemented by the brainstem “move to a place of safety – we need some energy for that – go and get some sugar.”
A similar analogy can be made for nicotine (and other) addiction(s). A smoker ‘knows’ in their cortex that smoking is bad for them, but the brainstem wants the dopamine hit. This is experienced at an emotional level, and the emotional drive tends to defeat more rational ‘cortical’ response every time, and so the smoker continues to smoke, even when they ‘know’ that it is harmful to them.
If anyone has had the experience of doing night shift work, they will well know the huge ‘slump’ feeling at 4 – 5am in the morning, the exhausted cortex says “I’m supposed to be eating sensibly right now,” but the brainstem is saying: “eat the sugar, eat the sugar, eat the sugar…” and this is experienced at an emotional level, the night shift worker will not feel OK until they have gone to the fridge and eaten the high sugar/ high carbohydrate food. This is purely the impact of increased ghrelin and reduced leptin, and it makes a lot of biological sense.
This is the reason why we see increased levels of obesity, hypertension, Type II diabetes, and then increased incidence of heart disease, stroke, and very likely dementia (as causal links here are starting to become established and recognised in the scientific literature) in those who have chronic sleep disturbance, particularly shift workers, and especially night shift workers.
Chronic tiredness is becoming increasingly common in the 24/7 society with work and social pressures encouraging people to sleep less in order to do more ‘life.’
We are also seeing increased consumption of caffeine, very often utilised to stave off tiredness; sedentary behaviours, as people are tending towards less activity; increased stress post-pandemic, with global energy and conflicts abounding; and increased use of blue screen devices, doom scrolling has entered our collective vocabularies and is absorbing time that previously might have been spent on more active social / energy consuming activities, we also are becoming increasingly aware of the negative health consequences of excessive social media usage. All of these are contributing to increased sleep disturbance across the developed world.
Protecting and preserving sleep then, is vital for both our physical and mental health generally, but also specifically in terms of glucose metabolism, appetite regulation and maintaining a healthy body weight.
There is a massive preponderance in society to focus on exercise and nutrition, and it may well be that an individual is eating good food and getting good levels of exercise, but if they are sleep deprived, they may still struggle to maintain a healthy body weight.
When sleep is managed well it is much easier to eat well, have sufficient energy to engage in exercise, and so to maintain healthy body weights. Indeed, obesity is a very common symptom of sleep disordered breathing (sleep apnoea.) A very common phenomenon for people living with sleep apnoea is that they tend to lose body weight quite swiftly after their apnoea is managed effectively, without necessarily changing exercise or nutrition regimes.
We may be able to ‘sleep ourselves thin’ if we place a focus on getting the right amount of good quality sleep rather than obsessing over exercise and nutrition regimes. Conversely, if we are obsessing over exercise and nutrition, but not optimising our sleep, then effective weight management may well be impossible, and this is all down to those two hormones, leptin and ghrelin, which are well beyond our conscious control.
Effective management and treatment of sleep problems
There are two approaches for managing insomnia approved by the National Health and Care Excellence (NICE) in the UK, namely sleeping medications, and Cognitive Behavioural Therapy for Insomnia (CBT-i.). At the present time no other interventions are approved by NICE as none have any significant (or even any) evidence to support their use, this includes the myriad ‘supplements’, sprays, teas and various ‘compounds’ like magnesium glycinate which are currently being aggressively marketed across the developed world.
General Practitioners (GPs) and other prescribers are reluctant to administer sleeping tablets as there are safety concerns over their usage. These medications can be: addictive; become less effective over time, so requiring increasing doses to be administered; cause grogginess and fatigue, potentially leading to accidents and time away from work; and they can impact negatively on daytime functioning as a result of so-called ‘hangover effects.’
As a result of this, NICE recommends CBT-i as the primary treatment pathway of choice for the person who is struggling with their sleep as the process is empowering for the client; teaching them skills to effectively manage their sleep problem, which they can then take away and use independently into the future without the need to return for repeat prescriptions.
CBT-i is very well researched, with now over a thousand studies going back to the mid-1990s; and has established success rates of around 70%, meaning that 7 out of 10 people with insomnia who engage with the process will see their symptoms improve into the healthy range (Morin et al., 2006). This is highly effective, sleeping medications may only achieve 30% at best. Hence NICE guidelines recommend CBT-i as the treatment pathway of choice, medications for insomnia are a second-line treatment, and a pretty poor second at that (NICE, 2026).
The process of CBT-i involves educating the client about sleep, and identifying where sleep can become compromised. Utilising a detailed assessment procedure clients then identify issues that may be significant for them (e.g. an inconsistent routine, being sedentary for long periods, consuming large amounts of caffeine, rising in the night to use the bathroom, excessive screen use – to name a few of the more commonly identified presentations), and then helping them to manage behavioural changes which can ameliorate the intrusion of ‘sleep antagonists’ on to their sleep.
The process also encourages engagement in ‘sleep promoting’ behaviours, such as tightening up routines and gaining exposure to natural daylight, which can both be highly effective interventions.
CBT-i is tailored to the individual and, as such, improves compliance and increases effectiveness. As a result, we see CBT-i as being highly effective as an intervention, as it is usually quite straightforward for a client to follow and to engage with this collaborative process.
Conclusions
These findings have stark implications for a 24/7 society, whereby many people are “optionally” sleeping less in order to maintain busy professional and social lives at the expense of getting enough, good quality sleep. Shift workers and night workers are particularly at risk groups.
Effective sleep management using highly effective, non-toxic psychological and behavioural interventions (CBT-i) would have profoundly positive outcomes not only for individuals, but also for Society at large.
Obesity is a modern-day health crisis, leading on to myriad other serious comorbidities including: Type II diabetes, hypertension, heart disease, stroke, and (very likely) dementia, the list goes on. Investing time, effort, energy and the public purse strings in managing sleep at a fundamental level will negate much illness, usage of healthcare services and cost; whilst improving quality of life and the ability to engage more fully with leisure, family, friends and remain in the workplace for longer, and so contributing into the public purse.
For those who are interested in more effective weight management, exercise regimes and nutrition are of obvious importance, but sleep management is so often overlooked and may well be the primary driver of appetite regulation, effective metabolism and essential for maintaining a healthy body weight.
If you or anyone you know is struggling with their sleep, the management of their body weight, or both then please do contact us for more information and guidance as required.
Read more
Teaching The World to Sleep by David R. Lee. 2nd Edition, 2023, Routledge, London. ISBN: 978-1-03-243513-8.
References
Aldabal, L. , & Bahammam, A. S. (2011). Metabolic, endocrine, and immune consequences of sleep deprivation. The Open Respiratory Medicine Journal, 5: 31–43.
Donga, E. , van Dijk, M. , van Dijk, J. G. , Biermasz, N. R. , Lammers, G. J. , van Kralingen, K. W., Corssmit, E. P. , & Romijn, J. A. (2010). A single night of partial sleep deprivation induces insulin resistance in multiple metabolic pathways in healthy subjects. Journal of Clinical Endocrinology and Metabolism, 95: 2963–2968.
Morin, C.M., Bootzin, R.R., Buysse, D.J., Edinger, J.D., Espie, C.A., & Lichstein, K.L. (2006). Psychological and behavioral treatment of insomnia: Update of the recent evidence (1998-2004) (AASM taskforce review). Sleep 29: 1398 – 1414.
Nedeltcheva, A. V. , & Scheer, F. A. (2014). Metabolic effects of sleep disruption, links to obesity and diabetes. Current Opinion in Endocrinology Diabetes and Obesity, 21: 293–298.
NICE Guidelines for Insomnia Treatment (2026.) https://cks.nice.org.uk/topics/insomnia/management/managing-insomnia/
Skoracka, K., Hryhorowicz, S., Schulz, P., et al. (2025). The role of leptin and ghrelin in the regulation of appetite in obesity. Peptides 186: 171367