This category page covers biotechnology and pharmaceutical companies developing therapies targeting circadian rhythm dysregulation and sleep-wake cycle disruption in Alzheimer's disease. Circadian dysfunction is both an early biomarker and a pathogenic driver in AD — the suprachiasmatic nucleus (SCN) and peripheral clocks become dysregulated, accelerating neurodegeneration through impaired glymphatic clearance, altered microglial activation, and disrupted metabolic homeostasis. Restoring circadian alignment represents a novel therapeutic approach targeting a fundamental yet underexplored dimension of AD pathophysiology[@musiek2016][@lananna2020].
The main therapeutic targets in this space include:
Mechanism: Melatonin receptor agonist (piromelatine)
Clinical Stage: Phase 2/3 (AD)
This category page covers biotechnology and pharmaceutical companies developing therapies targeting circadian rhythm dysregulation and sleep-wake cycle disruption in Alzheimer's disease. Circadian dysfunction is both an early biomarker and a pathogenic driver in AD — the suprachiasmatic nucleus (SCN) and peripheral clocks become dysregulated, accelerating neurodegeneration through impaired glymphatic clearance, altered microglial activation, and disrupted metabolic homeostasis. Restoring circadian alignment represents a novel therapeutic approach targeting a fundamental yet underexplored dimension of AD pathophysiology[@musiek2016][@lananna2020].
The main therapeutic targets in this space include:
Mechanism: Melatonin receptor agonist (piromelatine)
Clinical Stage: Phase 2/3 (AD)
Background: Neurim Pharmaceuticals is a specialty pharma company focused on circadian rhythm therapeutics. Piromelatine (TH-102) is a novel melatonin MT1/MT2 receptor agonist with additional serotonin 5-HT2C antagonist activity. It is being developed for AD patients with comorbid sleep disturbances and circadian dysregulation[@neurim2024].
Key Science:
Mechanism: Near-infrared photobiomodulation (PBM) via intranasal and/or transcranial delivery
Clinical Stage: Phase 2 (AD/PD)
Background: Vielight develops non-invasive neurostimulation devices using photobiomodulation — low-level laser/LED light in the near-infrared spectrum (810 nm). Their Neuro Alpha device combines intranasal infrared light delivery to the suprachiasmatic nucleus region with transcranial stimulation. PBM is theorized to enhance mitochondrial function in neurons, improve SCN clock function, and reduce neuroinflammation[@vielight2024].
Key Science:
Mechanism: Sigma-1 receptor agonist (AXS-12 — reboxetine analog with sigma-1 agonism)
Clinical Stage: Phase 2 (AD agitation — AXS-060); AXS-12 in preclinical/early clinical
Background: While Axsome's primary AD focus is AXS-060 (sigma-1 agonist for agitation), they have explored sleep-wake modulation through sigma-1 receptor pathways. The sigma-1 receptor is a chaperone at the endoplasmic reticulum-mitochondria interface that modulates calcium signaling, neuroplasticity, and circadian gene expression. Sigma-1 agonism may indirectly reinforce clock gene expression and improve sleep quality in AD[@axsome2024].
Key Science:
Mechanism: Dual orexin OX1/OX2 receptor antagonist (lemborexant)
Clinical Stage: Approved for insomnia (Dayvigo); Phase 2 trials in AD (SUNMOON trial)
Background: Eisai developed lemborexant (Dayvigo), a dual orexin receptor antagonist approved for insomnia disorder. In AD, Eisai is investigating whether orexin antagonism can improve sleep quality and potentially modulate AD pathology. The orexin system regulates wakefulness through hypothalamic neurons that project widely through the brain. In AD, orexin neurons may become dysregulated, contributing to fragmented sleep-wake cycles[@eisai2024][@eisai_lemp].
Key Science:
Mechanism: REV-ERB agonist / SIRT1 activator programs (discovery/early research)
Clinical Stage: Discovery
Background: Takeda has explored circadian clock modulators including REV-ERB agonists and SIRT1 activators as potential treatments for neurodegenerative diseases. The nuclear receptors REV-ERBα and REV-ERBβ are key components of the clock feedback loop — their agonism can reinforce BMAL1 expression and strengthen circadian amplitude. SIRT1, a NAD+-dependent deacetylase, regulates BMAL1 acetylation and links circadian rhythms to metabolic state[@takeda2024].
Key Science:
Mechanism: Bright light therapy / blue-enriched light exposure
Clinical Stage: Research / Clinical use (non-pharmacological)
Background: Multiple companies and academic medical centers offer bright light therapy devices for circadian entrainment in aging and neurodegeneration. While no single company dominates this space, it represents an important non-pharmacological approach. Philips (Somneo Sleepcare), Respi, and others have developed light therapy devices used in AD clinical settings to improve sleep-wake consolidation[@light2024].
Key Science:
| Company | Mechanism | Stage | Notes |
|---------|-----------|-------|-------|
| Lonza | NAD+ precursors (SIRT1 activation) | Research | NMN and NR for circadian clock support |
| ChromaDex | SIRT1 activator (NR) | Research | Targets metabolic circadian coupling |
| Cyclerion | REV-ERB agonist | Preclinical | CYhip-01 for circadian reinforcement |
| Roaring 20s | SIRT1 modulators | Discovery | Novel sirtuin modulators |
| AbbVie | Orexin programs | Discovery | OX1/OX2 antagonists for AD sleep disorders |
| Roche | Circadian biology | Research | Broad clock gene research program |
| UCB Pharma | Melatonin pathway | Research | MT1/MT2 focused drug discovery |
| Target | Drug/Program | Company | Mechanism | Stage |
|--------|-------------|---------|-----------|-------|
| Melatonin MT1/MT2 | Piromelatine | Neurim | Agonist — restores nocturnal signaling | Phase 2/3 |
| Near-infrared PBM | Neuro Alpha | Vielight | SCN stimulation — strengthens zeitgeber | Phase 2 |
| Sigma-1 receptor | AXS-060 | Axsome | Agonist — clock gene support | Phase 2 |
| Orexin OX1/OX2 | Lemborexant | Eisai | Antagonist — sleep normalization | Phase 2 (AD) |
| REV-ERB | CYhip-01 | Cyclerion | Agonist — reinforces BMAL1 | Preclinical |
| SIRT1 | NR/NMN | ChromaDex/Lonza | Activator — metabolic circadian coupling | Research |
| Light | Bright light | Philips/Signify | Zeitgeber — strengthens SCN | Clinical use |
| Orexin OX1/OX2 | Various | AbbVie | Antagonists | Discovery |
Melatonin (N-acetyl-5-methoxytryptamine) is the primary hormone of darkness, secreted by the pineal gland during the biological night. In AD, melatonin levels decline dramatically — even before clinical symptoms appear — and this decline correlates with circadian rhythm disruption. Melatonin acts through two G-protein coupled receptors (MT1 and MT2) that are widely distributed in the SCN, hippocampus, and cortex. Beyond sleep promotion, melatonin exerts antioxidant, anti-amyloid, and anti-inflammatory effects in the brain. Melatonin therapy in AD has shown improvements in sleep quality, sundowning, and potentially cognitive outcomes[@cardinal2012][@lin2019].
The orexin (hypocretin) system consists of hypothalamic neurons producing orexin-A and orexin-B peptides that signal through OX1 and OX2 receptors to promote wakefulness. In AD, orexin neuron function is disrupted, leading to sleep-wake fragmentation. Dual orexin receptor antagonists (DORAs) like lemborexant promote sleep by blocking orexin signaling, enabling patients to fall asleep and stay asleep more effectively. This is particularly relevant in AD patients with insomnia, where sleep fragmentation may accelerate amyloid clearance deficits[@sakurai2007].
SIRT1 (sirtuin 1) is a NAD+-dependent deacetylase that links cellular metabolism to circadian gene expression. SIRT1 deacetylates BMAL1 and PER2, modulating the clock transcriptional-translational feedback loop. SIRT1 activity follows a circadian rhythm and declines with aging — this decline may contribute to clock dysfunction in AD. SIRT1 activators (resveratrol, NAD+ boosters like NMN or NR) have shown benefit in AD models by restoring clock function and enhancing metabolic resilience[@lananna2020].
Light is the primary zeitgeber (time-giver) that entrains the SCN to the 24-hour day. In AD patients, reduced visual acuity, limited outdoor exposure, and institutional settings lead to inadequate light input, weakening circadian entrainment. Bright light therapy (morning exposure to 10,000 lux white light) strengthens SCN function, improves sleep-wake consolidation, and reduces circadian rhythm disorders in AD. The combination of morning bright light and evening melatonin represents a non-pharmacological first-line approach[@van2022].
The circadian/sleep therapeutic field for AD is emerging, with no approved disease-modifying treatments specifically targeting clock function in AD. Key differentiators:
| Approach | Advantages | Risks |
|----------|------------|-------|
| Melatonin agonists | Well-tolerated, addresses multiple pathways (sleep + neuroprotection) | Modest efficacy for sleep alone |
| Orexin antagonists | Direct sleep-wake normalization, approved for insomnia | May not address underlying clock dysfunction |
| Photobiomodulation | Non-pharmacological, no drug interactions | Device-based, limited reimbursement, variable delivery |
| SIRT1/REV-ERB | Targets core clock machinery, disease-modifying potential | Early stage, unclear translation |
| Light therapy | Safe, evidence-based, low cost | Compliance challenges, weak effect size |