Learning Center

Sleep - Its Effect on Performance & Cognitive Function

Written by Dr.Craig Liebenson, Certified Pain Management, Rehabilitation & Sports Health Professional

How a Lack of Quality Sleep Negative Impacts You

Cognitive & Emotional Effects of Adverse Sleep

Lack of Sleep & Physical Performance

6 Simple Ways to Improve Your Sleep


How a Lack of Quality Sleep Negative Impacts You

Did you know consistent sleep routines enhance both health and performance? From what time you go to sleep to how long you sleep and even how deeply you sleep. Those who have better sleep habits have been shown to not only perform better, but to be healthier. Many things influence your sleep. Such as stress levels, anxiety, physical activity, social isolation, pain, mattress comfort, how dark and cold your room is, afternoon or evening caffeine consumption, exposures to electronics before bed, and more. Essentially, sleep is of crucial importance and is influenced by a complex host of factors.

The science of sleep is an emerging field, but one that is crucial in the emerging field of lifestyle medicine. Chronic sleep restriction (i.e., ≤6 hr/night) is habitual for approximately 30% of U.S. adults (Dickinson 2019). Just 1-2 nights of bad sleep or a week or two less than ideal sleep influences both our mental and physical health [Belenky (2003), Spiegel (2009).

According to Heidi Prather, DO from the Hospital for Special Surgeries in New York City


She continues - the negative health effects of poor sleep, include:

  • Not being able to think clearly or perform tasks well the next day.
  • Feeling chronically tired.
  • oIncreased risk of cognitive issues, such as dementia.
  • Higher perception of pain.
  • Greater risk of cardiovascular disease, hypertension (high blood pressure) and metabolic disorders (such as type 2 diabetes) .
How a Lack of Quality Sleep Negative Impacts You

Cognitive & Emotional Effects of Adverse Sleep

Cognitive & Emotional Effects of Adverse Sleep

According to Dickinson et al, “commonly experienced adverse sleep states have significant effects on decisions under uncertainty.” (Dickinson 2019). It is not surprising then that lack of sleep reduces focus and cognitive function (Chennaoui 2021). A study by the Walter Reed Army Institute of Research determined that extended sleep deprivation reduces “perceived emotional intelligence (EQ) and constructive thinking skills,” which under ideal circumstances work together to allow “adaptive functioning,” - the ability to effectively deal with situations throughout each day, communicate clearly, and avoid conflict with others. (Killgore 2008).

Castillo (2022) reported that in a group dynamic “insufficient sleep increases coordination failure costs”. This is important to avoid the “trap of costly miscoordination and wasted cooperative efforts.” Optimizing sleep situations becomes critically important for public safety, in construction, police work, and health care environments where the cost of poor cognitive decisions is particularly high.

Sleep and mood or emotional state are intertwined. Poor sleep has been shown to negatively influence mood as well as be a risk factor for clinical depression (Villaume 2023). Villaume et al reported, “our findings show sleep to be an important risk factor and hence a promising point of intervention for improving mood and reducing the risk of future MDEs (major depressive episodes) in adolescents and early adults.” The authors report that sleeps dysfunction can predict depression even 5 years into the future.

Lack of Sleep & Physical Performance

Lack of Sleep & Physical Performance

Lack of sleep reduces performance by increasing neuromuscular fatigue. Good sleep habits can also aid recovery from injury possibly through controlling inflammation (Chennaoui 2021). A general guide is that getting less than 7-8 hours of sleep reduces cognitive abilities.

Losing just 1 night of sleep has been shown to negatively affect sport or physical performance while consistently having improved sleep over weeks or months has a positive effect (Fullagar (2015), Bonnar (2018), Vitale (2019).

Optimal sleep can enhance our energy, recovery, and strength. Going from 8 hours of sleep to 5 hours of sleep/night for a week decreased testosterone levels by 15% in young men (Leproult 2011). Since normal aging is associated with a decrease of testosterone levels of 1%- 2% per year sleep is needed to mitigate this loss. (Harman 2001).

Looking at injuries Chennaoui et al state, “The risk of muscle injuries is greater…when sleep duration decreases, and training load increases simultaneously, which can be exacerbated by fatigue.” The authors continue, “skeletal muscle, like virtually all cells in the body, has circadian rhythms, and recent studies have begun to demonstrate that disruptions in circadian rhythms (as sometimes encountered by elite and competitive athletes) can be detrimental to skeletal muscle health.

6 Simple Ways to Improve Your Sleep

1. Practice Good Sleep Hygiene

Good sleep hygiene is about developing a schedule of behaviors that are conducive to optimizing your sleep. Things such as sleeping early, waking at a set time, and ensuring not to eat or have a coffee before bedtime can be a gamechanger for someone that is lacking sleep. As simple as this method may seem, people still tend to procrastinate or come up with excuses to not make the necessary changes that could benefit them in the long run. If you are interested in making the change today to your sleep, my article on ‘Sleep Hygiene,’ could help you explore what you need to consider improving how you prepare for sleep.

Practice Good Sleep Hygiene
Create a Comfortable Sleeping Environment.

2. Create a Comfortable Sleeping Environment.

This is a bit of no brainer. If you are not comfortable, how can you possibly sleep? Comfort is a combination of things. It can be from the temperature of your room, the mattress you use, what you are wearing and even the light intensity of a bedroom space. We can go on for ages and debate what is comfortable, but you must realise comfort is subjective. A mattress that is comfortable for one person doesn’t mean that it is going to work for you. Since a mattress is the item, you sleep on usually each night.

3. Exercise & Engage in Physical Activity

Exercise has great benefits to health and regardless of whether you are exercising to improve sleep or not, physical activity is something that we need to keep doing to look after our overall well-being. Many people find that after engaging in physical activity, especially intense training, it can help reduce the on-set time for sleep. This means that it is possible you can get to sleep faster and maybe deeper for a restorative night’s rest. Make sure you set at least an hour aside during the day to do something breaks out a good sweat.

Exercise & Engage in Physical Activity
Be Mindful of How You Feel & Manage It

4. Be Mindful of How You Feel & Manage It

Research has shown that sleep is strongly implicated in the processing of daily stresses and emotions. It also reveals that people who are sleep deprived report increased negative moods such as anger, frustration, irritability, and sadness, and decreases in positive moods. A lack of sleep is especially harmful to the consolidation of positive emotional content, which can influence mood and emotional reactivity and is tied to mental health disorders and their severity, including the risk of suicidal ideas or behaviors. Stress can also reduce deep sleep and rapid eye movement (REM) sleep, both of which are important for mental and physical health. If how you feel or what you are thinking is disrupting your sleep, try finding ways to clear your mind. You can talk to friends or family, exercise or if required speak to a mental health professional.

5. Relaxation & Meditation

Stress can be good…sometimes. Helps to keep you focused on a goal or allows you to complete challenges, but I am talking about the good stress. If you feel overwhelmed, lethargic, or maybe not in the right state of mind perhaps you need to take some time to relax. Do the things you love to get your mind off things, or you can do some yoga or meditation activities. If you want to learn more about actual exercises or activities, you can read my article on the topic of ‘Mindfulness & Relaxation.’

Relaxation & Meditation
Limit Day Time Napping

6. Limit Day Time Napping

Believe it or not napping too long in the afternoon causes disruptions to your circadian rhythm making it even more difficult to sleep at night. Don’t nap late in the afternoon and try not to nap for more than 20-30 minutes. Ensure that your naps are always around midday, so that you are not experiencing delayed sleep at night.


Sleep deficits have been shown to impair cognitive function as well as negatively influence performance outcomes. The science of sleep is an emerging field. The current scientific literature shows many potential physiological pathways between sleep and mood, cognitive function, physical performance, and injury risk mitigation.

Preventive health care or lifestyle medicine places great emphasis on sleep duration and quality.

  • Ease of falling asleep at night
  • Sleep duration in hours
  • Fatigue and energy levels during the day

Optimization of sleep can have large positive effects on health, mood, cognition, and physical performance.

Dr. Craig

Check out our mattress here: