Sleep disturbances and fatigue in ankylosing spondylitis: A narrative review of prevalence, mechanisms, clinical impact and management

Sleep disturbances and fatigue are common and burdensome manifestations of ankylosing spondylitis (AS). They are strongly associated with overall disease burden and impaired health-related quality of life. This narrative review summarises current evidence on their prevalence, underlying mechanisms, clinical consequences, assessment and management. Sleep disturbances affect approximately half of patients with AS, while clinically significant fatigue is reported by a similar proportion of patients across axSpA populations. Both symptoms are associated with greater pain, higher disease activity, impaired physical function, psychological distress, reduced social participation, and poorer quality of life. Fatigue may also affect selected dimensions of occupational functioning. Their pathogenesis is multifactorial. Inflammatory signalling may contribute to both symptoms, with TNF-α having the clearest established role in sleep regulation and broader inflammatory pathways, including TNF-α and IL-17, potentially contributing to fatigue. Pain, restricted mobility, functional impairment, anxiety, depression, chronic insomnia, and coexisting sleep disorders may also play important roles. Anti-inflammatory treatment can improve fatigue and patient-reported sleep outcomes, although objective sleep findings remain inconsistent and residual symptoms may persist despite improvements in disease activity. Exercise, physiotherapy, patient education, and appropriate management of insomnia and coexisting sleep disorders may complement pharmacological treatment. Sleep quality and fatigue should therefore be assessed directly as distinct patient-reported domains. Further longitudinal and interventional studies using standardised outcome measures are needed to clarify causal relationships, determine symptom-specific treatment effects, and support more individualised management.