The Hidden Costs of Sleep Deprivation & Its Consequences

The Hidden Costs of Sleep Deprivation & Its Consequences

By Jeremy Sutton, Ph.D.

In the short term, a lack of sleep can leave us stressed and grumpy, unwilling or unable to take on what is needed or expected of us.

A prolonged reduction in sleep (sleep deprivation), results in a range of physical and mental health conditions, damaging our ability to perform or experience wellness (Ly, 2024).

While poor sleep reduces employee effectiveness in most workplaces, it can cost lives in demanding and critical environments such as health care and emergency services (Wolkow et al., 2019).

This article explores what’s stopping us from getting the sleep we need, what harm it can do, and what treatments are available.

What Is Sleep Deprivation?

Before looking at what we mean by sleep deprivation, it’s essential to understand what researchers consider normal.

Sleep experts differ on how to define normal sleep. This is partly because the act of measuring sleep typically disturbs the process. However, we know for sure that sleep normality varies between people and across settings (Bianchi, 2014).

Normal sleep is, therefore, best reported by the individual as the amount of sleep they need to feel fully rested and able to function well.

Balter and Axelsson (2024) found that when 186 people were asked to target nine hours of sleep over two consecutive nights, they reported feeling 0.24 years younger. When requested to restrict their sleep to four hours, they felt 4.44 years older.

Within sleep research, sleep deprivation is often defined as the brain state that arises from 24 hours of wakefulness (Wesensten, 2022).

However, when most people outside of a research setting discuss sleep deprivation, they typically mean falling below an average of seven to nine hours of sleep a night (Murugesu, 2024; Wilson, 2023).

Don’t panic if you are managing fewer hours of shut-eye. Other research suggests that our sleep duration may be genetically determined, and such “short sleepers” may not experience as many negative consequences as “long sleepers” being deprived of sleep (Wilson, 2023).

Common Causes for Lack of Sleep

Recent research has investigated the causes of poor sleep, sleep deprivation, and chronic sleep deprivation in various populations. The following are all factors in sleep disruption (Khemka et al., 2020; Lubas et al., 2019):

  • Work and study schedules — shift work, night shifts, and irregular working hours
  • Conflict — disagreements involving families and romantic relationships
  • Mental health conditions — such as anxiety and depression
  • Excessive social media usage — particularly the use of social media late at night, which impacts sleep patterns
  • Alcohol consumption — particularly when excessive
  • Caffeine — stays in the system for several hours
  • Poor sleep hygiene — lack of regular sleep schedules and exposure to stimulating activities before bedtime
  • Environmental factors — too much noise, light, and even the wrong temperature (too warm or too cold)
  • High stress — work, study, or relational stress
  • Medical conditions — chronic pain, sleep apnea, gastrointestinal issues, and neurological disorders
  • Medications — certain medicines, such as antidepressants and stimulants
  • Hormonal changes — specific life stages, such as puberty, pregnancy, and menopause
  • Sleep disorders — including sleep apnea, restless legs syndrome, and narcolepsy

While not exhaustive, the list above summarises some of the most common causes for a lack of sleep or interferences to sleep patterns.

13 Sleep Deprivation Symptoms & 5 Stages

The following is a list of symptoms associated with mild and extreme sleep deprivation. It is unlikely that an individual will have them all but may experience one or more (Khemka et al., 2020; Lubas et al., 2019; Cappuccio et al., 2018; Wolkow et al., 2019):

  1. Daytime sleepiness — feeling drowsy and excessively tired during the day at work, with friends, and studying
  2. Fatigue — a lack of energy or physical and mental exhaustion
  3. Decreased motivation — lowered drive and enthusiasm even for favorite hobbies
  4. Impaired memory and concentration — difficulty paying attention (particularly for long periods) and forgetting important details
  5. Poor cognitive function — including impaired decision-making and problem-solving skills
  6. Mood swings — increased irritability
  7. Reduced performance — lower productivity and performance
  8. Increased risk of accidents — reactions and coordination negatively affected; mistakes and accidents more likely
  9. Weakened immune system — more susceptible to illness and infection due to a compromised immune system
  10. Weight gain — gaining weight or difficulty losing it
  11. Increased risk of mental health issues — worsening mental health, such as depression and anxiety
  12. Headaches — more frequent headaches or migraines
  13. Increased cravings — increased appetite and hunger for unhealthy foods

While there is no agreed definition of the stages passed through with regard to sleep deprivation, here is a potential list (Nunez, 2023; Walker, 2018; Rise, 2024):

  • Stage 1 (24 hours without sleep) — Already, the impact on cognition, awareness, and attention is comparable to being over the legal alcohol limit for driving in all 50 US states. Symptoms include drowsiness, irritability, decreased alertness, impaired concentration, and fatigue.
  • Stage 2 (36 hours without sleep) — Attention span and reaction time are significantly reduced, and there is an increased number of involuntary microsleeps (brief episodes of unconsciousness) as well as difficulty learning new information.
  • Stage 3 (48 hours without sleep) — Individuals may be increasingly accident prone, experiencing possible hallucinations, and demonstrate severe negative impact on decision-making. Immune system may be weakened.
  • Stage 4 (72 hours without sleep) — At this stage, individuals may experience overwhelming sleepiness along with the risk of delusions and complex hallucinations. The individual exhibits disordered thinking and depersonalization (feelings of being outside yourself).
  • Stage 5 (96 hours without sleep) – Chronic sleep deprivation involves a severe distortion of reality and the unbearable urge to sleep. There are likely experiences of disordered thoughts, dissociation, and possible psychosis.

Symptoms will vary depending on the situation and the individual, and reactions may be experienced from multiple stages at any given time (Walker, 2018).

The Risks & Costs of Being Sleep Deprived

The risks and costs of sleep deprivation are complex and varied. While sleep is vital to mental and physical health in everyone, needs differ, and so does its impact when restricted (Balter & Axelsson, 2024).

The following is a list of several of the risks and costs, highlighting the negative impact of poor sleep.


There are many risks to our mental and physical performance associated with being sleep deprived.

– Brain & memory

Studies have highlighted the damage poor sleep can have on the brain, including declining cognitive performance as a result of its negative impact on brain functioning and memory (Malkani & Zee, 2020).

Sleep loss profoundly impacts our ability to solve problems and make decisions. It is highly damaging to mental health and has even been linked to the onset of Alzheimer’s disease (Khemka et al., 2020; Wu et al., 2019).

– Immune system

Various research has highlighted the risk of poor sleep to the immune system.

“Sleep deprivation makes a living body susceptible to many infectious agents,” leaving the body open to increased illness and disease (Asif et al., 2017, p. 92).

– Endurance

Along with sleep deprivation’s impact on cognitive performance, there are physical impacts, including harming the “interaction of the homeostatic and circadian neurobiological processes,” which may impact endurance (Hurdiel et al., 2018, p. 2).

Appropriate sleep strategies are vital in endurance sports, such as ultramarathons that may extend well beyond 24 hours (Hurdiel et al., 2018).


Lack of sleep has a cost — some direct, others indirect.

– Work-related costs

Research into sleep-deprived working mothers found they were likelier to engage in workplace deviant behaviors (such as lateness, intentionally making mistakes, and working slowly) and perform more poorly (Deng et al., 2022).

Poor sleep has also been shown to negatively impact the psychological and physical health of employees and is a risk factor for more severe and long-term illness (Peng et al., 2023).

– Education

Students often experience a lack of sleep due to increased socializing, irregular sleep schedules, academic demands, and excessive technology usage (Khemka et al., 2020).

The effects can be considerable. Khemka et al. (2020) identified sleep deprivation as impacting students’ ability to think critically, make decisions, and understand and retain information.

– Safety and high-risk jobs

A lack of sleep for safety, health care, and emergency workers can be harmful and dangerous (Walker, 2018).

A 2019 study of firefighters found that poor sleep — exacerbated by shift patterns — increased the risk of burnout and mental health problems. Sleep loss can potentially put safety workers and the general public in danger from poor decision-making and lack of judgment (Wolkow et al., 2019).

– Self-perception

Sleep is linked to physical and mental health and how we see and think of ourselves (Balter & Axelsson, 2024).

Each day of poor sleep has been shown to add, on average, 0.23 years to our perceived age (Balter & Axelsson, 2024).

A Take-Home Message

Many of us don’t get the quality or quantity of sleep we would like and, more importantly, need.

Persistent or prolonged insufficient sleep can significantly and negatively impact our mental and physical wellness. Outcomes can range from daytime sleepiness and impaired memory and cognition to accidents, potentially harming ourselves and others.

Sleep deprivation can result from parenting or workplace demands or ongoing interruptions from unwanted noise and light, impacting our sleep schedules and reducing our hours of slumber.

Stress can also have a significant impact. We may lie awake worrying about difficult conversations, troublesome colleagues, or our finances.

Several readily available treatments and lifestyle adjustments can help those experiencing sleep deprivation.

Improving sleep hygiene can support creating a sleep-positive environment that promotes quantity and quality of sleep. At the same time, more general tips can help align our daytime and nighttime habits with our circadian rhythms.

If you or your clients are facing temporarily disrupted sleep or, more crucially, ongoing sleep deprivation, the contents and links in this article will offer valuable opportunities to reduce the causes and effects.

Jeremy Sutton, Ph.D., is an experienced psychologist, consultant, and coach who blends academic excellence with practical experience to foster wellbeing, flourishing, and high performance in individuals and organisations.

This article first appeared on the Positive Psychology website.

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