{"id":"https://openalex.org/W1968064632","doi":"https://doi.org/10.1111/j.1365-2869.1992.tb00019.x","title":"In short photoperiods, human sleep is biphasic","display_name":"In short photoperiods, human sleep is biphasic","publication_year":1992,"publication_date":"1992-06-01","ids":{"openalex":"https://openalex.org/W1968064632","doi":"https://doi.org/10.1111/j.1365-2869.1992.tb00019.x","mag":"1968064632","pmid":"https://pubmed.ncbi.nlm.nih.gov/10607034"},"language":"en","primary_location":{"id":"doi:10.1111/j.1365-2869.1992.tb00019.x","doi":"https://doi.org/10.1111/j.1365-2869.1992.tb00019.x","is_oa":false,"landing_page_url":"https://doi.org/10.1111/j.1365-2869.1992.tb00019.x","pdf_url":null,"source":{"id":"https://openalex.org/S123151105","display_name":"Journal of Sleep Research","issn_l":"0962-1105","issn":["0962-1105","1365-2869"],"is_oa":false,"is_in_doaj":false,"is_core":true,"listed_in":["cwts-core","dongbi-b","doyens","jufo-1","ki-jl-1","medline","norway-1","poland-100","russia-white-list-1","vabb-shw"],"host_organization":"https://openalex.org/P4310320595","host_organization_name":"Wiley","host_organization_lineage":["https://openalex.org/P4310320595"],"host_organization_lineage_names":["Wiley"],"type":"journal"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Journal of Sleep Research","raw_type":"journal-article"},"volume":null,"type":"article","is_traditional":true,"indexed_in":["crossref","pubmed"],"open_access":{"is_oa":false,"oa_status":"closed","oa_url":null,"any_repository_has_fulltext":false},"authorships":[{"author_position":"first","author":{"id":"https://openalex.org/A5026475727","display_name":"Thomas A. Wehr","orcid":"https://orcid.org/0000-0002-4559-9964","observed_orcids":["https://orcid.org/0000-0002-4559-9964"]},"institutions":[{"id":"https://openalex.org/I1299303238","display_name":"National Institutes of Health","ror":"https://ror.org/01cwqze88","country_code":"US","type":"government","lineage":["https://openalex.org/I1299022934","https://openalex.org/I1299303238"]},{"id":"https://openalex.org/I4210158500","display_name":"National Institute of Mental Health","ror":"https://ror.org/04xeg9z08","country_code":"US","type":"facility","lineage":["https://openalex.org/I1299022934","https://openalex.org/I1299303238","https://openalex.org/I4210158500"]}],"countries":["US"],"is_corresponding":true,"raw_author_name":"THOMAS A. WEHR","raw_affiliation_strings":["Clinical Psychobiology Branch, NIMH, Bethesda, MD, USA"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Clinical Psychobiology Branch, NIMH, Bethesda, MD, USA","institution_ids":["https://openalex.org/I1299303238","https://openalex.org/I4210158500"]}]}],"institutions":[],"countries_distinct_count":1,"institutions_distinct_count":2,"corresponding_author_ids":["https://openalex.org/A5026475727"],"corresponding_institution_ids":["https://openalex.org/I1299303238","https://openalex.org/I4210158500"],"apc_list":{"value":4340,"currency":"USD","value_usd":4340},"apc_paid":null,"fwci":1.2253,"has_fulltext":false,"cited_by_count":118,"citation_normalized_percentile":{"value":0.71536429,"is_in_top_1_percent":false,"is_in_top_10_percent":false},"cited_by_percentile_year":{"min":88,"max":99},"biblio":{"volume":"1","issue":"2","first_page":"103","last_page":"107"},"is_retracted":false,"is_paratext":false,"is_xpac":false,"primary_topic":{"id":"https://openalex.org/T10342","display_name":"Circadian rhythm and melatonin","score":0.9243000149726868,"subfield":{"id":"https://openalex.org/subfields/2807","display_name":"Endocrine and Autonomic Systems"},"field":{"id":"https://openalex.org/fields/28","display_name":"Neuroscience"},"domain":{"id":"https://openalex.org/domains/1","display_name":"Life Sciences"}},"topics":[{"id":"https://openalex.org/T10342","display_name":"Circadian rhythm and melatonin","score":0.9243000149726868,"subfield":{"id":"https://openalex.org/subfields/2807","display_name":"Endocrine and Autonomic Systems"},"field":{"id":"https://openalex.org/fields/28","display_name":"Neuroscience"},"domain":{"id":"https://openalex.org/domains/1","display_name":"Life Sciences"}},{"id":"https://openalex.org/T10985","display_name":"Sleep and Wakefulness Research","score":0.04780000075697899,"subfield":{"id":"https://openalex.org/subfields/2805","display_name":"Cognitive Neuroscience"},"field":{"id":"https://openalex.org/fields/28","display_name":"Neuroscience"},"domain":{"id":"https://openalex.org/domains/1","display_name":"Life Sciences"}},{"id":"https://openalex.org/T11373","display_name":"Sleep and Work-Related Fatigue","score":0.016499999910593033,"subfield":{"id":"https://openalex.org/subfields/3205","display_name":"Experimental and Cognitive Psychology"},"field":{"id":"https://openalex.org/fields/32","display_name":"Psychology"},"domain":{"id":"https://openalex.org/domains/2","display_name":"Social Sciences"}}],"keywords":[{"id":"https://openalex.org/keywords/polyphasic-sleep","display_name":"polyphasic sleep","score":0.765999972820282},{"id":"https://openalex.org/keywords/short-day-photoperiod","display_name":"short-day photoperiod","score":0.8100000023841858},{"id":"https://openalex.org/keywords/sleep-consolidation","display_name":"sleep consolidation","score":0.5910000205039978},{"id":"https://openalex.org/keywords/circadian-rhythm","display_name":"circadian rhythm","score":0.6970000267028809},{"id":"https://openalex.org/keywords/melatonin-secretion","display_name":"melatonin secretion","score":0.9549999833106995},{"id":"https://openalex.org/keywords/sleepiness","display_name":"sleepiness","score":0.7680000066757202},{"id":"https://openalex.org/keywords/constant-routine","display_name":"constant routine","score":0.6819999814033508},{"id":"https://openalex.org/keywords/two-process-model","display_name":"two-process model","score":0.9290000200271606}],"concepts":[{"id":"https://openalex.org/C55969652","wikidata":"https://www.wikidata.org/wiki/Q259028","display_name":"photoperiodism","level":2,"score":0.8318202495574951},{"id":"https://openalex.org/C2778182776","wikidata":"https://www.wikidata.org/wiki/Q180912","display_name":"Melatonin","level":2,"score":0.8155679702758789},{"id":"https://openalex.org/C2777334680","wikidata":"https://www.wikidata.org/wiki/Q1607611","display_name":"Nocturnal","level":2,"score":0.7613836526870728},{"id":"https://openalex.org/C121446783","wikidata":"https://www.wikidata.org/wiki/Q208353","display_name":"Circadian rhythm","level":2,"score":0.6983720064163208},{"id":"https://openalex.org/C85181434","wikidata":"https://www.wikidata.org/wiki/Q11288132","display_name":"Dusk","level":2,"score":0.6829135417938232},{"id":"https://openalex.org/C2775841894","wikidata":"https://www.wikidata.org/wiki/Q4683692","display_name":"Sleep (system call)","level":2,"score":0.6718894839286804},{"id":"https://openalex.org/C134018914","wikidata":"https://www.wikidata.org/wiki/Q162606","display_name":"Endocrinology","level":1,"score":0.441967248916626},{"id":"https://openalex.org/C135343436","wikidata":"https://www.wikidata.org/wiki/Q170406","display_name":"Rhythm","level":2,"score":0.4391055703163147},{"id":"https://openalex.org/C126322002","wikidata":"https://www.wikidata.org/wiki/Q11180","display_name":"Internal medicine","level":1,"score":0.413875937461853},{"id":"https://openalex.org/C86803240","wikidata":"https://www.wikidata.org/wiki/Q420","display_name":"Biology","level":0,"score":0.39934009313583374},{"id":"https://openalex.org/C15744967","wikidata":"https://www.wikidata.org/wiki/Q9418","display_name":"Psychology","level":0,"score":0.35522186756134033},{"id":"https://openalex.org/C71924100","wikidata":"https://www.wikidata.org/wiki/Q11190","display_name":"Medicine","level":0,"score":0.30530744791030884},{"id":"https://openalex.org/C18903297","wikidata":"https://www.wikidata.org/wiki/Q7150","display_name":"Ecology","level":1,"score":0.0890229344367981},{"id":"https://openalex.org/C111919701","wikidata":"https://www.wikidata.org/wiki/Q9135","display_name":"Operating system","level":1,"score":0.0},{"id":"https://openalex.org/C41008148","wikidata":"https://www.wikidata.org/wiki/Q21198","display_name":"Computer science","level":0,"score":0.0}],"mesh":[],"locations_count":2,"locations":[{"id":"doi:10.1111/j.1365-2869.1992.tb00019.x","doi":"https://doi.org/10.1111/j.1365-2869.1992.tb00019.x","is_oa":false,"landing_page_url":"https://doi.org/10.1111/j.1365-2869.1992.tb00019.x","pdf_url":null,"source":{"id":"https://openalex.org/S123151105","display_name":"Journal of Sleep Research","issn_l":"0962-1105","issn":["0962-1105","1365-2869"],"is_oa":false,"is_in_doaj":false,"is_core":true,"listed_in":["cwts-core","dongbi-b","doyens","jufo-1","ki-jl-1","medline","norway-1","poland-100","russia-white-list-1","vabb-shw"],"host_organization":"https://openalex.org/P4310320595","host_organization_name":"Wiley","host_organization_lineage":["https://openalex.org/P4310320595"],"host_organization_lineage_names":["Wiley"],"type":"journal"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Journal of Sleep Research","raw_type":"journal-article"},{"id":"pmid:10607034","doi":null,"is_oa":false,"landing_page_url":"https://pubmed.ncbi.nlm.nih.gov/10607034","pdf_url":null,"source":{"id":"https://openalex.org/S4306525036","display_name":"PubMed","issn_l":null,"issn":null,"is_oa":false,"is_in_doaj":false,"is_core":false,"listed_in":[],"host_organization":"https://openalex.org/I1299303238","host_organization_name":"National Institutes of Health","host_organization_lineage":["https://openalex.org/I1299303238"],"host_organization_lineage_names":[],"type":"repository"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Journal of sleep research","raw_type":"Journal Article"}],"best_oa_location":null,"sustainable_development_goals":[],"study_designs":[],"awards":[],"funders":[],"has_content":{"grobid_xml":false,"pdf":false},"content_urls":null,"referenced_works_count":17,"referenced_works":["https://openalex.org/W1968000210","https://openalex.org/W1978655203","https://openalex.org/W2020921004","https://openalex.org/W2025390318","https://openalex.org/W2038215683","https://openalex.org/W2039164431","https://openalex.org/W2044445190","https://openalex.org/W2069642211","https://openalex.org/W2074643325","https://openalex.org/W2079962268","https://openalex.org/W2080268475","https://openalex.org/W2096352061","https://openalex.org/W2096832875","https://openalex.org/W2137473989","https://openalex.org/W2214874719","https://openalex.org/W3112761749","https://openalex.org/W3217417991"],"related_works":["https://openalex.org/W4386592772","https://openalex.org/W2038215683","https://openalex.org/W4387866517","https://openalex.org/W1968873836","https://openalex.org/W2174962221","https://openalex.org/W1970720667","https://openalex.org/W2001639868","https://openalex.org/W2084870711","https://openalex.org/W2058628483","https://openalex.org/W2104625718"],"abstract_inverted_index":{"Results":[0],"of":[1,17,60,65,69,84],"a":[2,26,51,74,124,128],"photoperiod":[3,29],"experiment":[4],"show":[5],"that":[6,81,87,107],"human":[7],"sleep":[8,16,36,89],"can":[9],"be":[10,112],"unconsolidated":[11],"and":[12,39,64,90,120],"polyphasic,":[13],"like":[14],"the":[15,66,82,100,108,134],"other":[18],"animals.":[19],"When":[20],"normal":[21],"individuals":[22],"were":[23],"transferred":[24],"from":[25],"conventional":[27],"16-h":[28],"to":[30,118],"an":[31],"experimental":[32,109],"10-h":[33],"photo-period,":[34],"their":[35],"episodes":[37],"expanded":[38],"usually":[40],"divided":[41],"into":[42],"two":[43],"symmetrical":[44],"bouts,":[45],"several":[46],"hours":[47],"in":[48,73,102],"duration,":[49],"with":[50,114,123],"1-3":[52],"h":[53],"waking":[54],"interval":[55],"between":[56],"them.":[57],"The":[58],"durations":[59],"nocturnal":[61,67],"melatonin":[62],"secretion":[63],"phase":[68],"rising":[70],"sleepiness":[71],"(measured":[72],"constant":[75],"routine":[76],"protocol)":[77],"also":[78],"expanded,":[79],"indicating":[80],"timing":[83],"internal":[85],"processes":[86],"control":[88],"melatonin,":[91],"such":[92],"as":[93],"circadian":[94],"rhythms,":[95],"had":[96],"been":[97],"modified":[98],"by":[99],"change":[101],"photoperiod.":[103],"Previous":[104],"work":[105],"suggests":[106],"results":[110],"could":[111],"simulated":[113],"dual-oscillators,":[115],"entrained":[116],"separately":[117],"dawn":[119],"dusk,":[121],"or":[122],"two-process":[125],"model,":[126],"having":[127],"lowered":[129],"threshold":[130],"for":[131],"sleep-onset":[132],"during":[133],"scotoperiod.":[135]},"counts_by_year":[{"year":2026,"cited_by_count":5},{"year":2025,"cited_by_count":6},{"year":2024,"cited_by_count":8},{"year":2023,"cited_by_count":5},{"year":2022,"cited_by_count":6},{"year":2021,"cited_by_count":7},{"year":2020,"cited_by_count":7},{"year":2019,"cited_by_count":5},{"year":2018,"cited_by_count":10},{"year":2017,"cited_by_count":4},{"year":2016,"cited_by_count":7},{"year":2015,"cited_by_count":8},{"year":2014,"cited_by_count":7},{"year":2013,"cited_by_count":7},{"year":2012,"cited_by_count":1}],"updated_date":"2026-11-07T11:25:07.637180","created_date":"2016-06-24T00:00:00"}
