Insufficient sleep, whether that’s due to poor sleep quality or other factors, is now a public health epidemic - and one that is notably unrecognised, under-reported and has high costs physically, mentally and economically. Sleep is one of our pillars of health, greatly influencing nearly every system in the body - from the brain to the heart, immune function, and beyond. Here’s a look into some of the ways sleep impacts your physical and mental health, why getting good sleep each night should be a priority, and some simple ways you can start promoting your sleep hygiene today.
The Interplay Between Sleep and Pain
If you’re living with an injury or pain, you should also know that pain and sleep share a bidirectional relationship that can significantly affect one’s quality of life.
How Pain Disrupts Sleep
Experiencing pain activates your nervous system which can make it difficult for your body to transition into the calm state required for sleep. Chronic pain conditions, such as arthritis or fibromyalgia, are closely associated with poor sleep quality. Studies reveal that up to 88% of individuals with chronic pain experience sleep disturbances, including difficulty falling and staying asleep. Both short sleep times and broken sleep can also heighten your sensitivity to pain. Even one night of poor sleep can heighten the body’s pain response, lowering pain thresholds and exacerbating discomfort the following day.
Can Improving Sleep Reduce Pain?
Thankfully, improving sleep quality has been shown to reduce pain levels over time. Restorative sleep allows the body to:
- Reduce inflammation, which plays a role in many chronic pain conditions.
- Enhance the nervous system’s ability to regulate pain signals.
- Promote tissue repair and healing processes essential for injury recovery.
Sleep and Recovery
Sleeping well plays an important role in your physical recovery. During deep sleep (also known as slow-wave sleep), the body engages in essential repair processes including:
- Muscle repair - growth hormone secretion peaks during deep sleep, facilitating muscle tissue repair and growth. Athletes who achieve sufficient sleep often experience faster recovery and improved performance. One study on 16-19-year-old athletes found that sleeping more than 8 hours during weekdays reduced the odds of injury by more than 60%.
- Cellular restoration - oxidative stress (which occurs when harmful molecules called free radicals build up in your body) is mitigated when you sleep. Sleep helps balance and neutralise these molecules, preventing damage to cells. Additionally, your body activates its natural repair mechanisms, allowing damaged cells to heal and regenerate more efficiently. Your cellular repair mechanisms also work most effectively as you sleep.
- Injury recovery - adequate sleep also enhances blood flow and tissue oxygenation, which helps you recover effectively from both injuries and surgical procedures.
Without sufficient sleep, these processes are disrupted, delaying recovery and increasing susceptibility to injuries.
Sleep and Chronic Diseases
Stroke, Heart Disease, and Blood Pressure
Inadequate sleep is strongly linked to cardiovascular issues. Chronic sleep deprivation has been shown to:
- Increase your blood pressure by activating the sympathetic nervous system, which raises stress hormone levels and constricts blood vessels.
- Disrupt circadian regulation of the heart, leading to irregular heart rhythms and elevated risks of stroke and heart attack.
- Increase inflammation, which plays a role in plaque formation within arteries (that leads to heart disease and issues).
Diabetes
When it comes to diabetes, being sleep-deprived can impair your glucose metabolism and insulin sensitivity, making the body less effective at managing blood sugar levels. A study published in 2024 found that people sleeping less than six hours per night are at a 28% higher risk of developing Type 2 diabetes compared to those getting 7-8 hours sleep per night.
Sleep Deprivation and Its Consequences
Beyond what we’ve detailed above, chronic (long-term) sleep deprivation has other far-reaching effects. Physically, sleep deprivation disrupts hormones that regulate hunger, leading to overeating and increased risk of weight gain and obesity. Cognitively, a lack of sleep significantly slows reaction times, hindering everyday tasks and posing serious safety risks, such as when driving or operating machinery. Studies have shown that even moderate levels of sleep deprivation produce impairments in a person’s cognitive and motor performance equivalent to legally prescribed levels of alcohol intoxication.
Sleep for Growth and Development
Sleep is vital for children and adolescents' growth and brain development from the moment they are born. When you’re in deep sleep, your body releases growth hormones essential for physical development, including for building muscle, strengthening bones, and supporting overall growth. Alongside physical growth, sleep is also integral to neurodevelopment. When you’re asleep, your brain engages in something called “synaptic pruning” where it removes unnecessary neural connections to optimise your brain functionality and efficiency. This helps refine learning, memory, and problem-solving skills, which are especially important as young people navigate their formative years. As adults, while our growth slows, sleep still remains absolutely essential for maintaining hormonal balance and emotions, repairing damaged tissues internally and externally, and generally best supporting our health and well-being.
Sleep and Immune Health
A well-functioning immune system depends heavily on sleep. During sleep:
- Cytokines, which help combat infections and inflammation, are produced in greater quantities.
- Sleep may support stronger antibody responses after vaccinations. Eight studies were reviewed regarding the sleep and immune response after vaccination (five of which were for influenza, two for hepatitis A, and one for hepatitis B). Six out of eight studies found a positive correlation between sleep and immune response after vaccination.
- Conversely, chronic sleep deprivation increases susceptibility to infections like colds and flu.
Sleep and Cognitive Function
Memory
When you sleep, you consolidate different types of memory. The first is declarative memory, which centres around facts, knowledge, and information you consciously learn. This type of memory benefits significantly from non-REM sleep, as here the brain transfers information from short-term storage into long-term memory, making it easier to retain and recall later. For example, studying for an exam or learning a new language relies heavily on getting good (sufficient) non-REM sleep.
The other is your procedural memory, which focuses on your skills and tasks, like when you’re riding a bike, playing an instrument, or developing in a sport. REM sleep helps you refine these abilities, as the brain processes and strengthens the connections needed to perform these tasks effectively.
Cognitive Performance
When you’re sleep deprived, your ability to solve problems, make decisions and maintain your focus can severely plummet. Your reaction times can also slow significantly, and even reach a critical level when doing things like driving or operating machinery.
Sleep and Mood
Ever find it harder to stay calm and collected when you haven’t had much sleep? Sleep deprivation affects your brain’s emotional centres and can disrupt how we process and regulate our emotions. The amygdala (the part of the brain which manages stress and emotional responses) becomes overactive, leading to heightened stress reactions and an exaggerated sense of threat. Your prefrontal cortex (the part responsible for logical thinking and emotional regulation) also loses its ability to keep these heightened emotions in check. The result is that you can find yourself much more likely to be irritable, feel a heightened sense of anxiety, or even be more prone to depression.
Sleep Hygiene: Practical Tips for Better Sleep
While there are some things we can’t control when it comes to our sleep, there’s a lot we can control, too - like our sleep hygiene. To improve your sleep quality, you can try:
- Sticking to a consistent sleep schedule and maintaining consistent wake-up and bedtime hours, even on weekends.
- Creating a sleep-conducive environment by using blackout curtains to eliminate light, keeping the room cool (around 18°C), and investing in a comfortable mattress and pillows.
- Limiting screen exposure by avoiding screens at least 90 minutes before bed and using blue light-blocking glasses if screen use is unavoidable.
- Minding your diet. Ideally, you want to avoid caffeine and nicotine 4-6 hours before bedtime and consume magnesium-rich foods, such as almonds and leafy greens, which may help promote relaxation. Avoiding late-afternoon naps.
- Exercising regularly, following our physical activity guidelines here in Hong Kong. Engage in moderate aerobic activity, which enhances slow-wave sleep, and avoid vigorous workouts within 2 hours of bedtime.
- Establishing a bedtime routine can also help by signalling to your brain that it’s time to wind down from your evening activities.
Physiotherapy For Better Sleep
If you have pain or other physical limitations that are impacting your sleep, our team here at PhysioCentral are here to help. Our highly experienced team of physios, podiatrists and osteopaths work using evidence-based and gold-standard strategies to help you get the best outcomes.
To book an appointment with our fantastic team, call +852 2801 4801 or book online.