Sleep-disordered breathing

The normal circadian rhythm of the body guides the sleep-wake cycle and resets approximately every 24 hours. Sleep is a complex physiological process, so that sleep disturbance and disorders are commonly seen in the general population. However, the risk is notably increased following a spinal cord injury (SCI).

Sleep disturbance

Key features

A range of signs and symptoms that characterise sleep disturbance can be experienced during the night or the day. These include:

  • insomnia, delayed sleep onset or sleep fragmentation
  • snoring, gasping or choking during sleep
  • abnormal leg movements during sleep
  • excessive daytime drowsiness and fatigue
  • reduced daytime executive functioning e.g. memory, concentration, decision making, reaction time, emotional regulation.

Key risk factors

The development of sleep disturbance is multifactorial, and may include normal risk factors as well as those specific to SCI.

These include:

  • high thoracic SCI, but especially a cervical SCI
  • disrupted circadian rhythm affecting melatonin regulation (cervical SCI may result in an interruption of sympathetic innervation to the pineal gland)
  • increased age
  • gender specific risk profiles for males (anatomical factors) and females (post-menopausal factors)
  • obesity and a large neck circumference
  • laryngeal muscle weakness related to post intubation or cervical spinal surgery
  • habitual supine sleep position
  • chronic pain and discomfort issues
  • high frequency leg movements during sleep
  • need to complete intermittent bladder emptying overnight
  • use of certain medications, including cardiac and antispasmodic agents
  • elevated consumption of alcohol and caffeine
  • use of sedatives and depressant substances
  • environmental factors, such as temperature, noise and light
  • psychological factors, including anxiety and depression.

Sleep disorders

Sleep disorders following SCI may include:
• sleep-disordered breathing (SDB), including both obstructive and central types
• movement-related disorders, such as restless leg syndrome and spasticity issues
• circadian rhythm sleep–wake disorders
• insomnia.

Sleep disturbances—particularly sleep disorders—can profoundly impact a person with SCI, affecting daily functioning, relationships, employment, and community participation. Untreated sleep disorders are associated with reduced quality of life and negative health outcomes, including chronic pain, depression, and cognitive decline.

Sleep-disordered breathing

SDB is of particular concern following SCI. A 2021 systematic review with meta-analysis reported that SDB in people with cervical SCI was prevalent at the following severity and rates: mild (83%), moderate (59%), and severe (36%). Increased prevalence was associated with older age. However, no statistically significant differences were found based on sex, body mass index, injury duration, injury completeness, or level of cervical injury.

Overall, the prevalence of SDB is reported to be 2-9 times greater in the SCI population, compared to the general population. Hence, SDB is a significant health issue to assess and manage.

The summary below outlines causative factors in the development of SDB following SCI, along with compounding factors.

Respiratory muscle weakness

Respiratory muscle weakness

  • Cervical and high thoracic SCI can result in weakness and paralysis of the diaphragm, intercostal, and accessory respiratory muscles.
  • Following extubation and cervical spinal surgery, upper airway muscles can become impaired.
  • During REM sleep, the natural reduction in muscle tone can worsen airway collapse and hypoventilation associated with SCI, increasing the risk of developing obstructive sleep apnoea (OSA).

Central respiratory control disruption

Central respiratory control disruption

  • SCI can interrupt descending pathways from the brainstem respiratory centres to the spinal cord.
  • During sleep, respiratory drive can be altered, increasing the risk of central sleep apnoea (CSA).

Autonomic nervous system disruption

Autonomic nervous system disruption

  • Cervical and high thoracic SC at or above T6, can result in ANS disruption, affecting control of upper airway tone and mucosal blood flow.
  • During sleep, airway collapsibility and ventilation-perfusion mismatch can occur, contributing to both OSA and CSA.

Compounding factors

Compounding factors

Compounding factors in the development of SDB following SCI are:

  • habitual supine sleep position
  • changes in metabolism and capacity to exercise, affecting body composition
  • certain medications
  • some lifestyle issues, such as hydration, substance use and sleep habits
  • inadequate prophylactic respiratory health practices, such as secretion management.

Assessment

A comprehensive assessment should involve a multidisciplinary team, the person with SCI and their support network.

General assessment may begin with noting subjective and objective indicators of sleep disturbance, including completion of various sleep screening questionnaires.

Specific assessment of SDB ideally involves polysomnography, which is an overnight sleep study using full diagnostic instruments. These typically include:

  • electrooculography (EOG)– to monitor eye movement to identify sleep stages
  • electroencephalogram (EEG)– to record brain wave activity
  • electrocardiogram (ECG)– to record heart electrical activity
  • pulse oximetry– to record heart rate and blood oxygen saturations
  • electromyography (EMG) leg sensors– to detect leg muscle contractions
  • infra-red video surveillance– to record overall rest versus sleep, as well as global body positions and limb movements.

Following SCI, full polysomnography is preferred, with interpretation of results and treatment trials overseen by a sleep /respiratory physician—rather than a sleep scientist. This is due to the complex risk factors for SDB that must inform both the interpretation of sleep study results and the overall management plan.

Preferred sleep study settings

The order of preference for sleep study settings is listed below, with some comments on considerations or limitations.

  1. Inpatient stay in a sleep clinic (with full diagnostics, including EEG)

This is strongly recommended for individuals with complex health needs or a history of significant respiratory admissions, as it provides the most comprehensive data and diagnostic detail about sleep and arousal.
The sleep clinic must accommodate specific access and care needs, such as:

  • appropriate equipment (e.g. hoist, sling, electric bed, pressure-relieving mattress, commode)
  • spacious rooms for equipment and safe manual handling
  • support for personal care and medication routines.

2. At home or inpatient hospital stay (outside of a sleep clinic with full diagnostics, including EEG)

This setting requires portable equipment, which may have reduced signal quality and lacks on-site sleep technician support. These limitations can affect data accuracy and result interpretation about sleep and arousal.

3. At home with limited diagnostics (without full diagnostics, including no EEG)
This option provides only basic data (e.g. pulse oximetry) and limited diagnostic detail about sleep and arousal.

Understanding sleep study outcomes

SDB often presents as a mixed pattern of obstructive and central sleep-disordered apnoea.

The apnoea–hypopnea index (AHI) is used as an outcome measure to diagnose and categorise SDB severity. It measures the total number of apnoea and hypopnea events per hour of sleep. In SDB, apnoea is defined as a period of no breathing for ≥10 seconds, while hypopnea is related to a ≥30% reduction in air flow, with a ≥3% drop in oxygen level or cortical arousal for ≥10 seconds.

An AHI score ≥ 5, is indicative of a degree of mild SDB, with increasing index scores attributed to increasing severity. People with SCI commonly experience a combination of both types of apnoea and hypopnea events.

Management

Untreated SDB following SCI is associated with a reduced quality of life and negative health outcomes, but also adverse health outcomes in comparison to the general population. These include a greater prevalence of lower respiratory tract infections, cardiovascular disease, hospitalisation, and ICU admissions. In addition to this, there is also a higher mortality rate from respiratory and cardiovascular conditions.

Therefore, SDB should be considered a high clinical priority in SCI management and promptly investigated. Completion of an initial sleep study should be followed-up by a repeat sleep study every few years—particularly as chronic respiratory dysfunction and ageing begins to impact respiratory health overall.

Lifestyle modifications and health management are important, but typically positive airway pressure (PAP) therapy during sleep is also required. A multidisciplinary team review is recommended to ensure a comprehensive approach and successful implementation.

Positive airway pressure therapy

Forms of PAP therapy, including continuous positive airway pressure (CPAP), are commonly used in the treatment of sleep apnoea following SCI. PAP therapy treats both the obstructive and central components of SDB following SCI, and is considered superior to newly developed oral devices and splints which may be used in the general population to manage mild SDB. PAP therapy is able to support upper airway patency, address nocturnal hypoventilation and compensate for aspects of autonomic dysfunction.

However, PAP therapy requires a significant investment in trialling and education to promote comfort and compliance, for therapeutic benefit. Potential barriers which may limit use of PAP therapy should be considered and addressed as possible. These include:

  • user tolerance—adjusting to the sensory and respiratory experience of assisted breathing during sleep
  • impaired upper limb function—may affect mask donning and doffing, leading to:
    • safety concerns
    • claustrophobia
  • insufficient overnight care support
  • a lack of accessible funding for equipment
  • limited implementation support from health professionals
  • a perceived lack of benefit—user may not notice immediate improvements.

CPAP Ventilation
Adapted from SCIRE Professional

Respiratory health management

Strategies may include:

  • reviewing adequacy of overall ventilation support
  • implementing lung volume augmentation
  • improving secretion management
  • treating other respiratory diseases eg. chronic obstructive pulmonary disease
  • reviewing hygiene practices
  • implementing a respiratory action plan.

Other health and supports management

Strategies may include:

  • addressing weight management through diet, exercise and caloric tracking
  • adopting a side-lying sleep position instead of supine, where appropriate—considering pain, pressure relief routines and functional independence
  • improving pain and spasticity management using stretching, positioning supports and medications
  • reviewing medications that may impair sleep
  • avoiding alcohol and caffeine, particularly in the evening
  • implementing sleep hygiene techniques such as regulating room temperature, reducing noise and light, maintaining a consistent bedtime, and trialling relaxation strategies
  • providing psychological support to address adjustment, anxiety, depression or other mental health concerns.

Discharge and community planning

A person with SCI who has SBD and needs to implement lifestyle and respiratory management, along with PAP therapy, may also need a review of their funding, care and health professional supports for community living.

For more information on these considerations, refer to Discharge and community planning.

Resources

Queensland Health Sleep Disorders Program: Information for clinicians
Queensland Health

Sleep Disordered Breathing After SCI
SCIRE Professional

Sleep Apnea
Craig Hospital

Respiratory Management Following Spinal Cord Injury: A Clinical Practice Guideline for Health-Care Professionals
Consortium for Spinal Cord Medicine—Clinical Practice Guidelines (USA)

Getting Your Zzz’s: Sleep Problems and Sleep Apnea in Persons with Spinal Cord Injury
University of Washington Rehabilitation Medicine

References

Berlowitz, D. J., Brown, D. J., Campbell, D. A., & Pierce, R. J. (2005). A longitudinal evaluation of sleep and breathing in the first year after cervical spinal cord injury. Archives of Physical Medicine and Rehabilitation, 86(6), 1193–1199. https://doi.org/10.1016/j.apmr.2004.11.033

Berlowitz, D. J., & Graco, M. (2024). Not there yet: The challenge of treating sleep-disordered breathing in people living with spinal cord injury/disease. Sleep, 47(5), zsae068. https://doi.org/10.1093/sleep/zsae068

Graco, M., McDonald, L., Green, S. E., Jackson, M. L., & Berlowitz, D. J. (2021). Prevalence of sleep-disordered breathing in people with tetraplegia: A systematic review and meta-analysis. Spinal Cord, 59(5), 474–484. https://doi.org/10.1038/s41393-020-00595-0

Graco, M., Berlowitz, D. J., & Green, S. E. (2019). Understanding the clinical management of obstructive sleep apnoea in tetraplegia: A qualitative study using the theoretical domains framework. BMC Health Services Research, 19(1), Article 405. https://doi.org/10.1186/s12913-019-4197-8

Sankari, A., Bascom, A. T., Chowdhuri, S., & Badr, M. S. (2014). Tetraplegia is a risk factor for central sleep apnea. Journal of Applied Physiology, 116(3), 345–353. https://doi.org/10.1152/japplphysiol.00731.2013

Sankari, A., Bascom, A., Oomman, S., & Badr, M. S. (2014). Sleep disordered breathing in chronic spinal cord injury. Journal of Clinical Sleep Medicine, 10(1), 65–72. https://doi.org/10.5664/jcsm.3362