Introduction: The Stress-Sleep Cycle

We often talk about stress and sleep as separate issues — but the truth is that they’re deeply connected. In our fast-paced world, stress can keep us wired long after the day ends, disrupting the very thing we need most to recover: sleep! At the same time, poor sleep lowers our ability to cope with stress, leaving us more reactive, more fatigued, and more vulnerable to burnout. In this blog, we’ll explore the science behind this two-way relationship, the real cost of poor sleep on mental health and productivity, and practical, evidence-backed ways to break the cycle.

What do we mean by stress? the dreaded “stress” word seems to be part of every realm of life. Put simply, Stress is the body’s response to demands or challenges that try to ‘unbalance’ it. These demands can be physical (eg. running), cognitive, psychological, or even emotional (eg. grief). Stress is innate to everyday life, triggered by a variety of things. Stress triggers the body’s fight-or-flight response, keeping you on high alert for any threats or demands. During this, the body releases the hormones cortisol & adrenaline, raising your heart rate and blood pressure, so that you are ready to react. This response is what keeps us safe in unsafe situations.

So stress is not necessarily a good or bad thing. What matters is how we respond to those triggers of stress. And sleep is fundamental to shaping this response. Stress and sleep work together in a feedback loop. Poor sleep leads to higher stress (van Dalfsen and Markus, 2018) and higher (especially long-term) stress leads to poor sleep (Kalmbach et al., 2018.And vice-versa, good sleep leads to lower stress. Good sleep allows the body to process stressful experiences and replenishes it’s resources for dealing with future stressors. But if we are constantly exposed to stress, getting to sleep is often very hard as our brains are active and unable to stop focusing on the potential danger. And it may lead to repeatedly waking up at night, disrupting the critical phases of sleep.

REM Sleep: Overnight Therapy

You may have heard of REM sleep, a phase of sleep critical for ensuring good mental and physical health. REM, standing for Rapid Eye Movement, is a critical state of sleep, characterised by rapid eye movements, heightened brain activity and muscle paralysis. It is during these periods that the majority of dreaming happens. REM sleep is associated with vivid dreaming and is thought to be crucial for processing emotions and negative experiences, potentially helping to lessen their impact on mental health (London, 2022). When we experience significant stress, individuals may experience & REM rebound, meaning an increase in REM sleep during subsequent sleep cycles, which can be a natural way to process and cope with the increased stressors (Summer & Rehman, 2024). But, if this REM sleep is disrupted or excessive, it can lead to worsened anxiety symptoms and nightmares (Summer & Rehman, 2024).

So, too much REM sleep can cause problems. That is why balance is key. The other side of the coin is called NREM (Non-rapid eye movement). The majority of our time spent asleep is spent in NREM, characterised by slow brain waves, relaxed muscles and a slowed heart rate. The deepest phase of NREM is called slow wave sleep, critical for both physiological and memory restoration. Slow wave sleep has been found to be related to the suppression of cortisol - commonly known as the stress hormone (Maud de Feijter et al, 2022). Disrupted or little sleep often means that this phase of slow wave sleep isn’t achieved, leading to heightened cortisol levels, and consequently higher stress. See here the dangerous feedback loop.

Credit: CatsKidsChaos, How to Break The Stress-Sleep Cycle (19.05.2020)

What Is the Cost of Bad Sleep?

Poor sleep doesn’t just leave you feeling groggy, it also disrupts the way you think, feel, and function on a day-to-day basis. Sleep plays a key role in memory consolidation, concentration, creativity, and even emotional regulation (Varney, 2018). Without enough quality sleep, we lose our ability to focus, communicate clearly, and adapt flexibly. This drop in cognitive performance can impact everything from everyday conversations to decision-making in high-stakes jobs.

Mood and mental health also take a mega hit. Sleep and depression have a bidirectional relationship: depression is one of the most common causes of insomnia (Berk, 2009), and prolonged poor sleep can, in turn, increase the risk of developing depression, due to impaired emotional regulation (O’Leary, Bylsma, & Rottenberg, 2016). Beyond low mood, fatigue and irritability are common symptoms, which often improve within days of good-quality sleep. But if poor sleep becomes chronic, it can contribute to more serious physical health risks — including elevated blood pressure, blood sugar imbalances, increased inflammation, and higher risk of heart failure and diabetes (Martire et al., 2020; Tobaldini et al., 2017).

How Sleep Deprivation Affects Work

In the workplace, the effects of sleep deprivation ripple out fast. People who sleep less than six hours per night are significantly more likely to miss work (absenteeism) or show up but perform poorly (presenteeism) (Hafner et al., 2017). This drop in performance often stems from cognitive impairments — slower reaction times, forgetfulness, and reduced attention to detail — which can be especially risky in roles requiring concentration and precision (Reynolds, 2016).

In fact, the economic cost of bad sleep is staggering: the UK loses more than 1.65 million working hours each year due to insufficient sleep (Hafner et al., 2017). Whether it's a missed deadline, a workplace error, or simply struggling to get through a normal day, the implications for both individuals and organisations are clear — improving sleep should be a key part of any productivity and well-being strategy.

How to Improve Your Sleep

The good news? Small changes can make a big difference. According to Bobo (2023), one of the most effective things you can do is establish a consistent sleep routine — going to bed and waking up at the same time every day helps regulate your body’s internal clock. Remember QQRT: Quantity, Quality, Regularity, and Timing. Keeping these somewhat consistent is key to healthy sleep. Being aware of your chronotype is also a key player in improving your sleep quality, as body clocks vary between individuals; science actually does explain that some people just really are not ‘morning people’! The peak hours of sleep for these ‘night owls’ is later on in the night, therefore waking up earlier, doesn’t align with their chronotype, and this in turn reduces their sleep quality.

Creating a sleep-friendly environment is equally important. That means:

Avoiding screens for two hours before bed
Practising simple body-based relaxation techniques (like shaking, tapping, Yoga Nidra, or body scan meditations)
Moving your body daily to support your natural circadian rhythm
Warm bath/shower followed by sleeping in a cool room.

Nutrition can also support better sleep. Limiting caffeine and alcohol — especially in the evening — is key. And certain foods, eaten a few hours before bed, may help promote sleep by increasing tryptophan, a precursor to serotonin (Zuraikat et al., 2022). Think: turkey, eggs, cheese, nuts, or a little dark chocolate.

Summary: Why Sleep Is a Non-Negotiable for Stress and Well-being

Sleep and stress are deeply intertwined — each one influencing the other in a continuous feedback loop. While stress is a natural and sometimes necessary response to life’s demands, chronic stress can disrupt our ability to fall and stay asleep. And without enough sleep, our brains and bodies become less equipped to manage stress, creating a cycle that’s difficult to break.

The science is clear: sleep is essential for emotional regulation, memory, creativity, and cognitive performance — all of which shape how we function both at work and in daily life. Poor sleep increases our risk of mental and physical health issues, and its effects ripple into the workplace in the form of absenteeism, presenteeism, and reduced productivity. The good news is that improving your sleep is often within reach. From building consistent routines and movement into your day, to embracing calming techniques and making strategic nutrition choices, small changes can make a big difference. By protecting our sleep, we equip ourselves with one of the most powerful tools for resilience, well-being, and long-term health.

The Scientific Link Between Stress and Sleep.