NICE vs SIGN: Management of Insomnia in Adults (2025) - A Clinical Comparison
This guide provides a detailed, factual comparison of the National Institute for Health and Care Excellence (NICE) and the Scottish Intercollegiate Guidelines Network (SIGN) guidelines for the management of chronic insomnia in adults. While both aim to improve patient care, their approaches, particularly in treatment recommendations, differ significantly. This resource is designed to help UK clinicians navigate these differences in their daily practice.
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Diagnosis and Assessment
Both NICE and SIGN align closely on the fundamental principles of diagnosing insomnia, emphasising a detailed clinical history as the cornerstone.
Shared Principles:
- Core Criteria: Both guidelines diagnose insomnia based on the DSM-5 or ICD-11 criteria, focusing on persistent difficulty with sleep initiation, duration, consolidation, or quality, despite adequate opportunity for sleep.
- Daytime Impact: The sleep disturbance must cause significant distress or impairment in daytime functioning (e.g., fatigue, mood disturbance, cognitive impairment).
- Comprehensive History: A thorough sleep history is essential, including sleep-wake patterns, pre-bedtime routines, and bedroom environment. Use of a sleep diary for at least 2 weeks is strongly recommended by both.
- Comorbidity Assessment: Crucial importance is placed on identifying comorbid medical (e.g., pain, COPD), psychiatric (e.g., depression, anxiety), and other sleep disorders (e.g., sleep apnoea, restless legs syndrome).
Key Differences in Assessment:
- Assessment Tools: SIGN provides more specific recommendations on the use of standardised questionnaires, such as the Insomnia Severity Index (ISI) to quantify severity and monitor treatment response. NICE mentions the importance of assessment but is less prescriptive about specific tools.
- Focus: NICE places a slightly stronger emphasis on assessing the impact of medications (prescribed and over-the-counter) and substance use (e.g., caffeine, alcohol) on sleep.
Treatment Recommendations: The Major Divergence
This is the area of greatest contrast between the two guidelines, primarily concerning the role of hypnotic medications.
First-Line Treatment: Strong Agreement
Both NICE and SIGN unequivocally recommend Cognitive Behavioural Therapy for Insomnia (CBT-I) as the first-line treatment for chronic insomnia.
- CBT-I: This multicomponent psychological intervention includes elements such as sleep restriction, stimulus control, cognitive therapy, and sleep hygiene education.
- Access: Both guidelines acknowledge the challenges in accessing trained CBT-I practitioners and encourage the use of digital CBT-I platforms (e.g., Sleepio, Sleepstation) as effective and scalable alternatives, where available through local formularies or the NHS.
Pharmacological Treatment: The Key Difference
The approach to hypnotic medication is the most critical practical difference for clinicians.
- NICE (NG235): Adopts a restrictive stance. It recommends that hypnotic medication should not be offered for the management of chronic insomnia, except as a short-term intervention during particularly stressful events or when CBT-I has failed and the insomnia is severe. The focus is on minimising long-term use due to risks of tolerance, dependence, and side-effects.
- SIGN (168): Presents a more pragmatic and nuanced approach. While reaffirming CBT-I as first-line, SIGN acknowledges that pharmacological treatment may be necessary for some patients. It provides guidance on the judicious use of hypnotics, including:
- Considering a short course of a hypnotic (e.g., a Z-drug or short-acting benzodiazepine) while waiting for CBT-I or if CBT-I is ineffective.
- Providing clear advice on the use of melatonin (for people over 55) and sedating antidepressants (e.g., low-dose amitriptyline or mirtazapine) in specific circumstances.
Practical Takeaway: A clinician in England and Wales following NICE may feel more constrained in prescribing hypnotics, whereas a clinician in Scotland following SIGN has guideline-supported options for considering medication in a managed way after a full discussion of risks and benefits with the patient.
Special Situations and Comorbidities
Both guidelines stress that insomnia comorbid with other conditions should be treated directly, rather than assuming it will resolve with treatment of the primary condition.
- Older Adults: Both highlight increased susceptibility to side-effects of hypnotics in this group. SIGN specifically recommends melatonin for insomnia in people aged over 55, whereas NICE is more cautious.
- Mental Health Comorbidity: In patients with comorbid depression/anxiety, treating the insomnia alongside the mental health condition is emphasised as it can improve overall outcomes. CBT-I is considered safe and effective in these populations.
- Pregnancy and Breastfeeding: Both guidelines advise extreme caution. Non-pharmacological management (CBT-I) is the absolute preference. If medication is essential, a risk-benefit discussion with a specialist is mandatory.
Practical Clinical Flow: A Synthesis
Combining the strengths of both guidelines, a robust UK clinical pathway can be suggested:
- Assessment: Take a comprehensive history, use a 2-week sleep diary, and assess for comorbidities and contributing factors (ISI questionnaire can be helpful).
- Diagnosis & Education: Confirm diagnosis of chronic insomnia. Provide information on sleep hygiene and the rationale for treatment.
- First-Line Treatment (Universal): Offer CBT-I (in-person or digital). Discuss the waiting times and benefits.
- Managing the Interim/Severe Cases:
- NICE-aligned: Avoid hypnotics. Focus on non-drug support. Only consider a very short-term prescription in exceptional circumstances.
- SIGN-aligned: If symptoms are severe or while awaiting CBT-I, consider a short-term (2-4 weeks), limited quantity prescription of a hypnotic, or a sedating antidepressant/low-dose melatonin (if over 55), with a clear plan for review and discontinuation.
- Review and Follow-up: Monitor response to CBT-I or medication. If first-line treatment fails, reconsider comorbidities and refer to a sleep specialist if needed.
Frequently Asked Questions (FAQs) for Clinicians
1. Which guideline should I follow if I practice in Scotland or England?
You should primarily follow the guideline relevant to your national health service: SIGN in Scotland and NICE in England and Wales. However, understanding the other guideline provides valuable context, especially for complex cases where a more flexible approach may be beneficial.
2. A patient has failed CBT-I and still has severe insomnia. What does NICE recommend?
NICE states that if CBT-I is unsuccessful, a referral to a specialist sleep service should be considered. Pharmacological treatment is not recommended as a second-line option by NICE, highlighting a significant management challenge. In practice, many clinicians would review the case for missed comorbidities or consider a medication trial informed by the SIGN guidance, documenting the decision-making process thoroughly.
3. What is the role of melatonin in adults according to these guidelines?
SIGN explicitly recommends considering melatonin for the treatment of insomnia in people aged over 55 years. NICE does not recommend melatonin for primary insomnia in adults, restricting its use mainly to sleep-wake cycle disorders. This is a key difference in prescribing practice.
4. Are over-the-counter (OTC) sleep aids recommended?
Both guidelines discourage the use of OTC antihistamine-based sleep aids (e.g., diphenhydramine) for chronic insomnia due to limited evidence of efficacy, anticholinergic side-effects, and the risk of tolerance.
5. How can I improve access to CBT-I in my practice?
Both guidelines endorse digital CBT-I (dCBT-I) as an effective solution. Clinicians should familiarise themselves with locally commissioned digital services (e.g., via the NHS Apps Library) and self-referral pathways. Advocating for increased commissioning of both digital and in-person CBT-I services is crucial.
Source Links
- NICE Guideline NG235 (May 2022): Insomnia
- SIGN Guideline 168 (March 2023): Management of Chronic Insomnia