{"id":"440a7c92-4549-5c88-9b46-1f7f7c9d6d0b","stable_key":"3279ff78-2460-5064-bfc0-3f2987af85a0:melatonin-b12-amplitude","predicate":"reduces_reported","statement":"Melatonin rhythm amplitude before the light exposure was smaller during the B12 condition.","claim_class":"observational","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"f1c8da7a-1d77-5903-bb9d-fcffd173d0fc","mechanism_event_label":"A lower amplitude and a shifted clock are separate measurements.","subject":{"id":"6563fbad-ebdc-5408-966a-d24f8b8cd854","slug":"methylcobalamin","display_name":"Methylcobalamin","entity_type_key":"small_molecule"},"object":{"id":"65a2f565-311b-5e9f-aa35-d0004f29ccdc","slug":"melatonin-rhythm-amplitude","display_name":"Amplitude of endogenous melatonin rhythm","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"f1c8da7a-1d77-5903-bb9d-fcffd173d0fc","stable_key":"3279ff78-2460-5064-bfc0-3f2987af85a0:melatonin-b12-amplitude-event","event_type":"observed_intervention","label":"A lower amplitude and a shifted clock are separate measurements.","description":"Melatonin rhythm amplitude before the light exposure was smaller during the B12 condition.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"6563fbad-ebdc-5408-966a-d24f8b8cd854","slug":"methylcobalamin","display_name":"Methylcobalamin","entity_type_key":"small_molecule"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"65a2f565-311b-5e9f-aa35-d0004f29ccdc","slug":"melatonin-rhythm-amplitude","display_name":"Amplitude of endogenous melatonin rhythm","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""}]},"contexts":[{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/melatonin-research/8981490.abstract.txt\", \"locator\": \"Primary indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"d0079778f8efe44c1538b9c85d56b12a3a766b734aab19660419fd461ec22792\", \"start_char\": 0, \"end_char\": 895, \"text_sha256\": \"d0079778f8efe44c1538b9c85d56b12a3a766b734aab19660419fd461ec22792\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Single-blind crossover light-response experiment","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Methylcobalamin IV 0.5 mg/day for 11 days then oral 6 mg/day for seven; morning 2500-lux light for three hours","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Small pharmacological B12 study, not B12-deficient participants. Does not establish a routine sleep treatment or increased melatonin production.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Melatonin research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"melatonin","display_name":"Melatonin","entity_type_key":"small_molecule"}},{"dimension":"organism","value_text":"Eight young men","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"A lower amplitude and a shifted clock are separate measurements.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[melatonin-p8981490] Vitamin B12 enhances the phase-response of circadian melatonin rhythm to a single bright light exposure in humans. (1996). https://pubmed.ncbi.nlm.nih.gov/8981490/ DOI: 10.1016/s0304-3940(96)13247-x","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Circadian melatonin rhythm","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"f9701f4b-2c4f-5573-b875-a25f05c656ca","evidence_kind":"source_excerpt","locator":"Lines 812-823","start_line":812,"end_line":823,"excerpt":"### melatonin-b12-amplitude\nMelatonin rhythm amplitude before the light exposure was smaller during the B12 condition.\nCondition category: normal\nnutrient_topic: Melatonin research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: A lower amplitude and a shifted clock are separate measurements.\norganism: Eight young men\ntissue_or_cell_type: Circadian melatonin rhythm\nexperimental_model: Single-blind crossover light-response experiment\nlimitations: Small pharmacological B12 study, not B12-deficient participants. Does not establish a routine sleep treatment or increased melatonin production.\nexposure: Methylcobalamin IV 0.5 mg/day for 11 days then oral 6 mg/day for seven; morning 2500-lux light for three hours\nevidence_span: {\"source_cache\": \"artifacts/melatonin-research/8981490.abstract.txt\", \"locator\": \"Primary indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"d0079778f8efe44c1538b9c85d56b12a3a766b734aab19660419fd461ec22792\", \"start_char\": 0, \"end_char\": 895, \"text_sha256\": \"d0079778f8efe44c1538b9c85d56b12a3a766b734aab19660419fd461ec22792\"}\n[melatonin-p8981490] Vitamin B12 enhances the phase-response of circadian melatonin rhythm to a single bright light exposure in humans. (1996). https://pubmed.ncbi.nlm.nih.gov/8981490/ DOI: 10.1016/s0304-3940(96)13247-x","model_system":"Single-blind crossover light-response experiment","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [melatonin-p8981490] Vitamin B12 enhances the phase-response of circadian melatonin rhythm to a single bright light exposure in humans. (1996). https://pubmed.ncbi.nlm.nih.gov/8981490/ DOI: 10.1016/s0304-3940(96)13247-x","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"bab588de-d217-5038-9c8b-b41222eba08b","stable_key":"import-3279ff78-2460-5064-bfc0-3f2987af85a0","title":"Melatonin: synthesis, receptors, circadian timing and nutrient interactions (2026-09-17)","document_type":"imported_text","citation_label":"AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. 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