Fatigue Issue 2: Fatigue and Sleep

By Ganymede


Closely linked to fatigue, and perhaps its most significant cause, is the amount and quality of sleep an individual receives. The consensus among scientists who study human performance and safety is that sleep is a powerful and vital biological need, which is as important to health as eating, drinking and breathing. Sleep aids recovery from mental as well as physical exertion and is vital for maintaining good mental and physical health, as it allows bodies to repair themselves and brains to consolidate memories and process information.


Quality of Sleep

There are two types of sleep that a person needs: rapid eye movement (REM) and non-REM sleep. REM sleep is where an individual dreams and non-REM is where they do not. We experience both types of sleep several times during the night, at different periods, with periods of non-REM sleep normally becoming progressively deeper. If a person does not get enough of both types of sleep, it can affect mood, energy and concentration levels, relationships, and their ability to stay awake and function at work during the day.

Sleep quality is also affected by the body’s circadian rhythms, which regulates different functions of the body to an average 24.2-hour cycle. The circadian rhythm has peaks and troughs, with the ‘low point’ typically occurring in the early hours of the morning. Sleep during this time has greater restorative value, and if consistently awoken during this time, the individual is likely to experience a depressed mood and is unlikely to perform at an optimum level.

Causes of Fatigue and Sleep Loss

The causes of sleep loss/disruption are many and varied, and include:

  • Work routines

  • Medical/generic conditions

  • Naturally changing sleep patterns as we age

  • Sleeping in surroundings that are not conducive to sleep: too warm or too cold, an uncomfortable bed, too much light, too noisy, etc. anxiety, stress, depression, life changes etc

  • Food (particularly caffeine) e.g., too much coffee, fizzy drinks, chocolate, etc

  • Alcohol, nicotine and other drugs

  • Napping and sleeping during the day

  • Medications and herbal remedies

  • Travel

  • Exercise e.g. too little or too much

Work related factors may include:

  • Long work hours

  • Long hours of physical or mental activity

  • Insufficient break time between shifts

  • Changes to jobs or shift rotations

  • Inadequate rest

  • Excessive stress

  • Having multiple jobs

  • Availability of resources

  • Work tasks which are long, repetitive, paced, difficult, boring and monotonous

  • The work environment (e.g. lighting, ventilation, temperature, etc.)

  • Combination of these factors


There are also various sleep conditions that may cause fatigue, including:

Insomnia: where a person cannot fall asleep, or cannot stay asleep for a full night. Insomnia can be both short term (in response to a stressful event or change in environment) and long term.


Sleep Apnoea: a breathing disorder in which there are brief interruptions (lasting a minimum of 10 seconds) in breathing during sleep, which is caused by a narrowing (or collapse) of the throat or upper airway during sleep.


Restless Legs Syndrome: where sensations of creeping, crawling, pulling or tingling can cause an irresistible urge for a person to move their legs.


Narcolepsy: a rare condition associated with sudden sleep ‘attacks’, where a person will have an uncontrollable urge to sleep many times in one day.

If you have any questions regarding the topics covered in our Fatigue series, please don't hesitate to get in touch with our HSEQ team on 0333 011 2048 who will offer you support and guidance.