What A Leader Should Know About Sleep

By John Axelsson & Tina Sundelin

In this article, the authors lift the lid on the pitfalls of a lack of adequate sleep – in terms of both quality and quantity, and how leaders are hindering their productivity when sleep deprived.


Sleep is a curious phenomenon. Despite more than 50 years of research, its biological function or functions remain elusive. Most recently, sleep has been shown to support vital brain functions relating to metabolism and adaptation. We do know that the high metabolism of the waking brain is a messy and costly business, and that sleep facilitates maintenance and recuperative functions by repairing the body’s machinery and structures from the day’s wear and tear. During sleep, we refill local energy stores and effectively clean up and remove metabolic rest products and toxic protein fragments.  There is also a growing body of evidence indicating that sleep plays a crucial role in how we adapt to our environment. During sleep, the brain repeats what it has experienced during the day so that the episodes and behaviours are incorporated into the already existing neural networks. This will also allow the brain to update and fine-tune these networks every night so that they become more efficient and stable. For example, movements that we have practiced during the day, such as playing the piano or hitting a curve ball, become more fluid and efficient after a night of sleep. Sleep is also likely to be a key player in the brain’s ability to learn vast amounts during the day and subsequently forget what is not used regularly. This way, the brain is ready to learn anew after a period of sleep. In other words, sleep seems to be the price for having a nervous system that can continuously adapt to each individual’s environment.


Sleep Disturbances are Common

While most adults should sleep between 7-9 hours per night to stay healthy, almost a third of the working population sleep less than 6 hours on a regular basis. Disturbed sleep is also common. As many as 30% of the adult population report having disturbed sleep and around 10% fulfil the clinical criteria for insomnia. In addition, a growing number of people suffer from sleep apnea, the risk factors of which are overweight, drinking alcohol, smoking, being male and increased age. In addition, about 25-30% of the working population are shift workers, and about 20% of the working force report having work-related sleep disturbances. Along with the fact that disturbed sleep shows a high comorbidity with other diseases, often aggravating the symptoms, there is a large need for improved screening and interventions focusing on prevention and treatment of sleep disturbances.


Sleep Loss is a Health Risk

Chronic disturbed sleep increases the risk for developing metabolic disorders such as cardiovascular disease, type 2 diabetes, and obesity. Furthermore, it may aggravate the risk for developing depression and Alzheimer’s disease.1 But even just a few days of decreased sleep increases the risk of contracting the common cold when exposed. Prioritising your sleep is thus a good choice, both in the long and short run.


Sleepy People are Error and Accident-Prone

Sleep loss and shift work are related to an increased risk for errors and accidents, particularly at the workplace. Several reports have found that sleep-related fatigue was a contributing factor to large-scale accidents such as Three Mile Island, Chernobyl, and Exxon Valdes. Long working hours (>10 hours/day) and extended workweeks (>60 hours/week) are particularly risky. For example, the long work shifts and work weeks amongst medical residents are related to reduced sleep, attentional failures, as well as serious diagnostic and medical errors. The increased risk for diagnostic errors with these kinds of shifts was more than 400% higher as compared to a schedule that has eliminated extended work shifts.2 Driving home after a long night shift is also a particularly risky situation. Few are well suited for the monotony of driving after being awake for such a long time, and being inattentive for a few seconds can be fatal.

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Sleepy People are Dull, Fickle, and Forgetful

Sleep loss leads to reduced brain activity in many brain regions, particularly in those networks critical for attention and perception, as well as for coordinating the resources needed for an optimal response. The fact that these networks are involved in many cognitive functions can explain why sleep loss leads to a number of cognitive impairments. Without sleep most people experience a general cognitive slowing, including making more errors, having problems concentrating for longer periods of time, and an impaired memory. When sleep loss increases or becomes chronic, the ability to keep up one’s attention becomes progressively more difficult.

Still, the most prominent sign of a sleep-deprived brain is that performance becomes unstable and starts fluctuating, from normal, unaffected performance to complete inattention. The fluctuations are probably caused by intrusions of local sleep. A number of recent findings show that the need for sleep can be so great in localised brain areas that they fall asleep, despite the rest of the brain still being awake. A crucial aspect here is that we are often aware of being very sleepy prior to episodes of involuntary sleep, but often fail to recognise or remember such episodes afterwards. This makes people relatively reliable at judging their sleepiness, but unreliable at judging whether they have actually fallen asleep while working and performing.

Still, the most prominent sign of a sleep-deprived brain is that performance becomes unstable and starts fluctuating, from normal, unaffected performance to complete inattention.

Sleep supports a number of memory processes, including memory formation and maintenance. Firstly, a fully rested brain is more flexible and will encode new memories better than a sleep deprived and tired one. Secondly, during sleep the brain will process the newly learnt memories so that they become consolidated and fine-tuned. Thus, sleep allows the brain to learn new things each day, as well as reprocess recent events so that the neural networks are constantly updated to better suit the present environment. This updating and fine-tuning has been proposed as a mechanism to why people may become more creative and find more divergent solutions to problems after a good night’s sleep.


Sleepy People are Moody, Aggressive, and Less Social

Lack of sleep makes people sleepy, moody, confused and impatient. In studies with several days of restricted sleep, people gradually reported feeling more angry and bad tempered, as well as feeling less optimistic and friendly.3 A study evaluating emotional reactivity in medical doctors found that sleep loss made people react more strongly to negative events. Brain-imaging studies indicate that emotion-focused areas of the brain react more strongly to emotional stimuli when sleep deprived. The reason could be that sleep-deprived people also show reduced activity in brain areas that regulate emotions. The disconnect between the regulating areas and so-called emotional areas can explain why sleep deprivation leads to problems controlling one’s impulses and emotions. While most people will not become violent due to lack of sleep, it has been proposed that, in vulnerable individuals, sleep loss can lead to rash decisions and violence.4 Accordingly, there is value in treating sleep disturbances in order to prevent aggressiveness and problematic behaviour.


Sleepy Brains and Higher Cognitive Functions

There is an increasing body of knowledge showing that sleep loss can disrupt complex cognitive processes such as working memory, reasoning, emotion regulation, behavioural inhibition, and executive functions. However, there is still a debate between researchers on the effects of sleep loss on many of the higher cognitive functions.5 The strongest consensus is that sleepy people have poorer working memory capacity, exemplified by a decreased ability to keep and manipulate information in one’s mind, as well as remembering words and order of events. Considering that sleep loss reduces the activity in the more executive parts of the brain (the prefrontal cortex), the effects on these functions are not as general and disastrous as one might have expected. The cognitive abilities which are most resilient to sleep loss seem to be rule-based reasoning, planning, and executive functions.6 A reason for this may be that people can compensate for the sleep loss by allocating extra resources, i.e. activating larger brain areas, when engaging in such tasks. These abilities are thus behaviourally resilient, but they need more energy and brain resources to operate at the same level.

Nevertheless, sleep loss is likely to drastically affect work-place performance, contributing to aspects such as information loss, neglect of important tasks, and missed learning opportunities.7


Sleep and Risky Decisions

Successful business is dependent on accurate communication, people being capable of critical thinking, and taking calculated risks. These aspects are so far little studied in sleep research, but there are indications that sleepy individuals are more impulsive, less likely to detect threats, and more likely to focus on rewards rather than potential losses. One reason could be that insufficient sleep is related to poor self-regulation the following day, self-regulation being very important for not giving in to temptations. There is some indication that sleepy people are more likely to make risky decisions, but more research is needed in this area.


Sleep, Social Interactions and Leadership

Expressions such as “you look tired” and “I need my beauty sleep” are common in many societies. Sleep-deprived people are indeed perceived as more tired, less healthy and less attractive.8 Although attractive people are favourably treated in a number of ways, for example, being judged as more social or better leaders, these effects are rather small. There are a number of indications that sleep loss can affect team performance, since word fluency, language processing and verbal creativity are affected, but surprisingly little data on this field exist.

In a recent study on the effects of day-light saving time, it was shown that judges gave harsher punishments (5% longer prison sentences) on the Monday after losing an hour of sleep as compared to Mondays the week before or after.

Poor sleep quality, but not sleep quantity, has been indicated as a culprit in more abusive behaviours for work supervisors, as indicated by both themselves and their subordinates.9 One reason for these effects could be that sleep loss seems to make people more prejudiced and less morally aware.10 In a recent study on the effects of day-light saving time, it was shown that judges gave harsher punishments (5% longer prison sentences) on the Monday after losing an hour of sleep as compared to Mondays the week before or after.11

In a series of studies on leadership in naval officers, it was shown that sleep loss made the officers have impaired moral reasoning, as well as having lower scores for transformational and transactional leadership and higher scores on passive-avoidant leadership.12 Sleep loss also resulted in an impaired ability to foresee important problems and a switch to a more rule-based reasoning. These studies are clearly suggesting that sleep loss affects planning skills and leadership effectiveness. Despite this, there is a need for more research on how sleep loss affects real behaviour in social and work settings.


How To Support Good Sleep

In order to improve sleep, one should take into account two important processes. One is the circadian system, which makes us sleep during the night and be awake during the day. However, this biological clock is not exactly 24 hours in most people, and we are instead dependent on regular daylight exposure to set it. In modern society, were many people spend little time outdoors but are exposed to hours of indoor lighting after sunset, this system struggles to keep up. The lack of daylight exposure in combination with evening light causes the clock to drift, resulting in more evening-prone people. A series of recent studies indicate that almost all people would become morning people within a few days of exposure to natural daylight only.13 Regular bedtimes and spending more time outdoors, particularly in the morning, helps the circadian system promote better sleep at night. The other important process is homeostasis, a process which means that your sleep need increases the longer you are awake. In cases of short or disturbed sleep, this need is only partially satisfied, meaning that you reach higher levels of sleepiness sooner after waking up.

In addition, sleep is a highly dynamic phenomenon, strongly affected by individual differences such as age, sex, stress exposure, disease, physical activities, alcohol, and medication. On the basis of homeostatic pressures, one can improve sleep by engaging in physical activities, regular sleep, and avoiding stress, alcohol, and medications. Napping should be seen as an effective way to compensate for sleep loss and to prevent fatigue at the work place (people suffering from insomnia should be careful at taking naps since they may make it more difficult to fall asleep). Naps should preferably be between 10-30 minutes, since they are very effective at the same time as they limit the risk for sleep inertia when awakened.


Figure 1: Participant after sleep deprivation (left) and after a normal night’s sleep (right).



Sleepiness is highly prevalent in many workplaces, affecting how people feel, think, and perform. Sleepy workers have a heightened risk of making errors, particularly if tasks demand a high degree of attention, or are monotonous. Also cognitive tasks involving emotion and memory processes are likely vulnerable to sleep loss as well. Sleep loss may further affect many social dimensions, including social perception and communication. Awareness of sleepiness, one’s own and others, is important since the causes and consequences can be managed by screening and treatment of sleep disorders, avoidance of extremely long shifts, introducing “healthy shift schedules”, and allowing regular recovery.


About the Authors

John Axelsson is a Professor at the Stress Research Institute, Stockholm University, and affiliated at the Department of Clinical Neuroscience, Karolinska Institute. With his research he aims to increase the knowledge and awareness of how sleep in the rapidly developing 24-hour society affects health, cognitive processes and social behaviour.


Dr. Tina Sundelin has a PhD in psychology from Stockholm University, Sweden and is currently a Postdoc at Karolinska Institutet, Sweden, and New York University, USA. Dr. Sundelin studies cognitive and social effects of sleep loss.




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