Glossary of Fatigue Terms

Term In a personal setting Further explanation in Module: In a workplace or safety environment setting Further explanation in Module:
Mental fatigue It is a gradual waning of mental capacity which may lead to accidents in the home or becoming unproductive. A fatigued mind usually results from either a lack of sleep or from being awake for a long time. It is a gradual waning of mental capacity to perform tasks, often leading to incidents, poor productivity or sleep onset (micro-sleeps, etc). A fatigued mind usually results from either a lack of sleep or from being awake for a long time. Most modules in relation to safety
Physical fatigue Physical fatigue relates to the body’s muscles and organs becoming tired or inactive due to excessive workload such as playing sport or undertaking strenuous tasks. Physical fatigue relates to the body’s muscles and organs becoming tired or inactive due to excessive workload and/or environmental conditions such as heat, humidity, wind, etc. Most modules in relation to safety
Sleep restriction A lack of sleep refers to not obtaining the correct amount of sleep for your age and physical condition (short-term or long-term) or through sleep impacted by sleep disorders, stress, pain or environmental impacts (noise, heat, etc). Sleep Restriction & Disorders, A lack of sleep refers to not obtaining the correct amount of sleep for your age and physical condition (short-term or long-term) or through sleep impacted by sleep disorders, stress, pain or environmental impacts (noise, heat, etc). Can be exacerbated by sleep conditions at camps, on vessels, etc. Most modules in relation to safety
Sleep debt When you do not sleep for the correct amount of time (or your sleep is broken/interrupted) you will develop a sleep debt. You need to pay back a sleep debt or it tends to carry over across several days. Sleep debts can be built up over a single night or over several nights and will lead to experiencing mental fatigue. The Science of Sleep An acute sleep debt will cause fatigue onset, especially at circadian low points. This may cause incidents due to poor performance, slow reaction times or micro sleeps. An employee has a duty of care to report if they are affected by fatigue and they should attempt to pay the debt back as soon as possible or seek help if needed. Most modules in relation to safety
Nap A 20-minute nap can be used at home if a person is feeling tired and wants to get a bit of energy without affecting sleep later that night. A brief nap allows a person to get into light stages of sleep only. If the person sleeps for longer, then 90-minutes is recommended to allow for one whole cycle of sleep. The Science of Sleep A 20-minute nap is often used as a countermeasure when a driver or employee is experiencing extreme fatigue leading to micro-sleeps. The 20 minutes allows the person to obtain light sleep (stages 1 & 2) but not move into deep sleep. If the employee gets into deep sleep, they may wake with sleep inertia. Most modules in relation to safety
Sleep inertia That very sleepy feeling you have when you wake from deep sleep. It may cause the person to stay unproductive for quite a while. Dangerous to drive or operate machinery at this point of inertia. The Science of Sleep That very sleepy feeling you have when you wake from deep sleep. If in the workplace or operating machinery, it may cause incidents due to poor coordination, slow reaction times and poor judgment. Best to wait until feeling fully aroused before recommencing any tasks. Most modules in relation to safety
Sleep wave In a bedtime context, a sleep wave is the perfect opportunity to go to sleep in a short period of time. It is easy to stay awake through the sleep wave but this often leads to missing the opportunity and getting a ‘second wind’. The Science of Sleep In a safety context, a sleep wave is that feeling where you have trouble staying awake often leading to micro sleeps if attempting to remain vigilant. At this point the situation may be dangerous. An employee should immediately stop work and speak with a supervisor. Most modules in relation to safety
Micro sleep Moving from being awake into stage 1 sleep and possibly stage 2 sleep for a brief period of time and usually in a non-desirable situation. It can be in front of the TV or at the wheel of a vehicle, leading to serious accidents. It is the brain’s way of trying to pay back a sleep debt. Most modules in relation to safety Moving from being awake into stage 1 sleep and possibly stage 2 sleep for a brief period of time, leading to unsafe situations. It is termed a ‘micro sleep’ as it is often interrupted by movement or sound (as in driving a vehicle) but can continue into full sleep if not interrupted. Most modules in relation to safety
Sleep onset Falling asleep in the appropriate context of being in bed or a position for safe sleep. This is often measured (latency) in cases of sleep disorders. The Science of Sleep In a workplace context, a sleep onset becomes a micro-sleep. The Science of Sleep
Sleep stage and sleep cycle

 

There are different sleep stages (one, two, three, four and rapid eye movement) and all five of these stages make up a sleep cycle of around 90 minutes. A good sleep for a normal, healthy adult would include five cycles of sleep. The Science of Sleep There are different sleep stages (one, two, three, four and rapid eye movement) and all five of these stages make up a sleep cycle of around 90 minutes. A good sleep for a normal, healthy adult would include five cycles of sleep. The Science of Sleep
Deep sleep

 

Stages three and four make up deep sleep. The brain becomes quite inactive although short-term memories are transformed to long-term. The brain produces human growth hormone for distribution to the body cells and serotonin for use in the brain. Immunity is supported in deep sleep. Necessary to promote good physical health. The Science of Sleep Stages three and four make up deep sleep. The brain becomes quite inactive although short-term memories are transformed to long-term. The brain produces human growth hormone for distribution to the body cells and serotonin for use in the brain. Immunity is supported in deep sleep. Necessary to promote stamina and resilience. The Science of Sleep
Sleep walking & sleep talking These are two of the disorders that usually occur in deep sleep. The cerebellum, which allows muscle movement and co-ordination, is active in deep sleep allowing a person to get out of bed, walk, talk and sometimes even eat. It is often not a serious issue unless the person walks out of the house or accommodation they are in. Sleep Restriction & Disorders These are two of the disorders that usually occur in deep sleep. The cerebellum, which allows muscle movement and co-ordination, is active in deep sleep allowing a person to get out of bed, walk, talk and sometimes even eat. Only an issue if it restricts sleep and causes a sleep debt. Sleep Restriction & Disorders
REM sleep Rapid eye movement sleep refers to the stage of sleep whereby the eyes move in their sockets with the eyelids closed. In babies and children, this is where a considerable amount of brain development occurs. Dreams mostly occur in REM sleep. The Science of Sleep Rapid eye movement sleep refers to the stage of sleep whereby the eyes move in their sockets with the eyelids closed. REM sleep assists with sorting stressful issues and enhancing memory for procedures in the workplace. The Science of Sleep
Sleep paralysis In rapid eye movement sleep, the cerebellum becomes inactive and the result is paralysis of the body. If a scary dream occurs and the person wakes up quickly, often the paralysis is still present until the cerebellum becomes active again. Although it seems like a long time, it is often only a few seconds. Sleep Restriction & Disorders In rapid eye movement sleep, the cerebellum becomes inactive and the result is paralysis of the body. If a scary dream occurs and the person wakes up quickly, often the paralysis is still present until the cerebellum becomes active again. Only an issue if the awakenings cause sleep debt. Sleep Restriction & Disorders
Night terrors Some children experience what is termed ‘night terrors’ which appear to be nightmares which cause the child to scream or appear very disturbed. Most often the child cannot remember the terror and the parent is the one who generally suffers from being awoken of disturbed by the child’s screams. Children & Education Some children experience what is termed ‘night terrors’ which appear to be nightmares which cause the child to scream or appear very disturbed. It is only a workplace issue if the parent is suffering from sleep restriction due to arousals or stress from worrying about the child. Children & Education
Sleep disorders There are over 70 known disorders of which the most common relate to insomnia, sleep disordered breathing or medical-sleep disorders. Any sleep disorder should be investigated and managed for good physical and mental health. Sleep Restriction & Disorders There are over 70 known disorders of which the most common relate to insomnia, sleep disordered breathing or medical-sleep disorders. Sleep restriction caused by disorders present safety issues in the workplace and should be investigated and managed as soon as recognised as part of an employee’s and employer’s duty of care. Sleep Restriction & Disorders
Insomnia Sleep onset insomnia is the inability to get to sleep when desired. Sleep maintenance insomnia relates to waking up through the normal sleep period, often unable to get back to sleep quickly. Terminal insomnia is a condition whereby the sufferer wakes up much earlier than intended. Sleep Restriction & Disorders Sleep onset insomnia is the inability to get to sleep when desired. Sleep maintenance insomnia relates to waking up through the normal sleep period, often unable to get back to sleep quickly. Terminal insomnia is a condition whereby the sufferer wakes up much earlier than intended. Safety at work may be compromised due to sleep restriction. Sleep Restriction & Disorders
Obstructive Sleep Apnoea

 

An apnoea is a breathing cessation often caused by a collapsing of the upper airway. The breathing cessation follows exhaling and the sufferer will have serious physical issues such as a rapid heartbeat, high Co2 levels, low blood oxygen saturation levels and high risk of stroke. It is a serious condition which requires treatment as soon as it is recognised. Sleep Restriction & Disorders An apnoea is a breathing cessation often caused by a collapsing of the upper airway. The breathing cessation follows exhaling and the sufferer will have serious physical issues such as a rapid heartbeat, high Co2 levels, low blood oxygen saturation levels and high risk of stroke. Safety at work may be compromised due to sleep restriction. Sleep Restriction & Disorders
Restless Legs Syndrome The condition with symptoms that are hard to describe, such as: “itchy legs”, “just have to move my feet”, or “feels like bugs under my skin”. Often caused by a lack of magnesium but can also be due to other dietary or physical conditions. Will cause distress at bedtime for the sufferer and the bed partner and requires correcting. Sleep Restriction & Disorders The condition with symptoms that are hard to describe, such as: “itchy legs”, “just have to move my feet”, or “feels like bugs under my skin”. Often caused by a lack of magnesium but can also be due to other dietary or physical conditions. Will cause distress at bedtime for the sufferer and the bed partner and requires correcting. Safety at work may be compromised due to sleep restriction. Sleep Restriction & Disorders
Hypnogogic jerk

 

Hypnogogic means: “going towards sleep” and the ‘jerk’ is often associated with a ‘jerking’ movement as one approaches sleep. Some people associate it with a dream whereby you are falling. Sleep Restriction & Disorders Hypnogogic means: “going towards sleep” and the ‘jerk’ is often associated with a ‘jerking’ movement as one approaches sleep. Some people associate it with a dream whereby you are falling. Rarely an issue. Sleep Restriction & Disorders
Hypnogogic hallucination A hallucination you have as you are going to sleep. This may be caused by a serious sleep debt as you do not normally dream or hallucinate when going to sleep. Only an issue if it is repeated often. Sleep Restriction & Disorders A hallucination you have as you are going to sleep. This may be caused by a serious sleep debt as you do not normally dream or hallucinate when going to sleep. Rarely an issue. Sleep Restriction & Disorders
Sleep clinic A sleep clinic is normally an environment designed for the measurement of sleep disorders. Some disorders are now capable of being investigated in a person’s home where they can sleep in their own beds. Sleep Restriction & Disorders A sleep clinic is normally an environment designed for the measurement of sleep disorders. Some disorders are now capable of being investigated in a person’s home where they can sleep in their own beds. Organisations can enlist the services of sleep professionals to better manage workplace safety. Supervisor Employee Fatigue Risk Management
Fatigue Management Policy A fatigue management policy is the organisation’s promise to its employees, the investors and the public, that it will operate in such a manner as to not cause employee fatigue and will manage fatigue in the workplace. The document is only useful if it is supported by a strong fatigue management plan. Supervisor Fatigue Compliance
Fatigue Management Plan A fatigue management plan is the process whereby the organisation sets out in detail, how fatigue risk will be identified and controlled. It will include information from all sections of the organisation, it will identify those responsible to ensure the processes and procedures are carried out and it will be communicated with all employees of the workplace. Finally, it will be measured and reviewed regularly. Supervisor Fatigue Compliance and Fatigue Risk Assessment (not online)
Fatigue risk Assessment A fatigue risk assessment work shop is used to assess all operations to identify fatigue risk in the workplace. As a minimum, it will involve representatives of different organisational sectors, a facilitator and a fatigue risk content expert. A report will follow with recommendations for fatigue controls, timelines and people responsible for ensuring controls are utilised. Fatigue Risk Assessment (not online)
Journey Management Plan A journey management plan is used to ensure that journeys undertaken by employees of an organisation are fatigue risk assessed and controls identified for company travel. They are also used to ensure employees arrive at work accommodation or travel home from work accommodation, in a safe manner and using the controls identified. They should be developed in conjunction with each employee undertaking travel. Fatigue Risk Assessment reports and Fatigue Management Plans (not online)
EAP An Employee Assistance Provider (EAP) is sometimes used by organisations to assist employees with issues of mental health, sleep disorders or stressful situations (amongst other things). They are an important component of employee wellness and their use should be encouraged by supervisors and management. Supervisor Employee Fatigue Risk Management
Fatigue Incident Investigation An investigation targeting fatigue involvement in an incident. In non-work settings, a fatigue incident investigation may be carried out to assist Police to determine if fatigue was a factor in a motor vehicle crash or other transport accident. Fatigue Incident Investigation Training (not online). An investigation targeting fatigue involvement in an incident. Requires the assistance of a fatigue subject content expert who is also experienced in incident investigation. In occupational settings, a fatigue incident investigation can assist to apply adequate controls to prevent similar occurrences from happening in the future. Fatigue Incident Investigation Training (not online).