‘I just snapped’. These words are often part of an unfolding anger outburst, as a colleague irrationally responds to an entitled manager, or a parent to a misbehaving child. These situations are often ones in which inappropriate intensity of anger and hostility is dealt out by a tired, sleep-deprived individual. Inadequate sleep plays havoc with our emotions.


Matthew Walker, the famous author of "Why We Sleep", has conducted many experiments to fully understand the negative consequences of sleep deprivation on our brains. One such study was using an MRI brain scanner to monitor how sleep deprivation influences the emotional brain at a neural level. Two groups of healthy adults were studied, one group stayed awake all night, while the other had a full eight hours of restful sleep. The next day, all participants were shown the same one hundred pictures that ranged from neutral (e.g. a basket) to emotional content (e.g. a burning house). Using an emotional gradient of pictures, Walker was able to compare the increase in brain response to the increasingly negative pictures. The brain scans revealed that the amygdala (the part of the brain that is responsible for triggering strong emotions such as anger, and is linked to the fight-or-flight response) had over 60% more emotional reactivity in those people who were sleep-deprived. In contrast, the brain scans of the group, who had a full 8 hours of sleep revealed a modest degree of reactivity in the amygdala. This is despite viewing the same images. Without sleep, we tend to have a pattern of uncontrolled, inappropriate emotional reactions.


Although insufficient sleep tends to put the brain into a negative ‘mood state’, it does not hold it there. Instead, we tend to swing (excessively) to both extremes of negative and positive emotions. Although it may seem that positive emotions should counterbalance your negative ones and neutralize the problem, this is not the case. It may rather trigger mental illnesses, such as depression and bipolar disorder. It has recently been reported that South Africa’s suicide rate is four times the global rate. Although sleep deprivation may not be the only cause, poor sleep can impact on a person’s inclination to moodiness or depression, and of course, this often leads to a downward spiral.


The prefrontal cortex, that part of the brain associated with rational, logical thought and decision-making, is also deeply affected after a poor night’s sleep. Without sleep, we have little rational control, and therefore an imbalance of emotional control. Whether you lose an entire night sleep or sleep less than 7 hours per night for a few nights in a row, your ability to think critically, clearly and/or decisively is all reduced and compromised. Driving your car after a poor night’s sleep is like driving with a blood alcohol content of 0.08%, which is over the legal limit! In fact, car accidents caused by drowsiness tend to be more deadly than those caused by alcohol or drugs. The reason for this is that drunk drivers brake too late, or don’t turn quickly enough in responding to other obstacles. However, when a drowsy driver has a microsleep, which is when the eyelids either partially or fully close, the brain becomes blind to the outside world for a brief moment. The control of your actions, such as steering or braking, momentarily freeze, and you stop reacting altogether.


The emotional reactivity resulting from sleep deprivation not only affects our personal lives, but our social ones too. Emotional intelligence is also greatly impaired with little sleep, which makes us less able to understand other people’s feelings, emotions, and experiences. So instead of blaming others for your crankiness and sharp temper, ask yourself how well you have managed your sleep lately. Such a seemingly insignificant activity in our lives can have long-lasting effects on our healthy, safety, wellbeing, and relationships. As E. Joseph once said: ‘The bridge between despair and hope is a good night’s sleep.”



Resilient People is a business that is abundantly and relentlessly focused on ways to empower individuals and teams to be more resilient in the workplace today.

Through the use of pragmatic Resilience Assessments, Workshops and Key Note Talks, Resilient People crafts bespoke programmes for their clients. The focus is on sustainable behaviour change, taking team by team on a practical, relevant journey.

Joni Peddie is a Professional Speaker, Executive Coach and Strategic Facilitator. She is determined to build awareness in SA about sleep being the key to good health and resilience.


Resilience is a skill needed in the 4th Industrial Revolution, to enable us to bounce back from adversity and do so with AGILITY!