Researchers now believe that he was suffering from space adaptation syndrome, which affects about a third of astronauts during their first day in space as their vestibular system adapts to weightlessness.
ɹᵻsˈɜːtʃɚz nˈaʊ bᵻlˈiːv ðæt hiː wʌz sˈʌfɚɹɪŋ fɹʌm spˈeɪs ˌædæptˈeɪʃən sˈɪndɹoʊm, wˌɪtʃ ɐfˈɛkts ɐbˌaʊt ɐ θˈɜːd ʌv ˈæstɹənˌɔːts dˈʊɹɹɪŋ ðɛɹ fˈɜːst dˈeɪ ɪn spˈeɪs æz ðɛɹ vɛstˈɪbjʊlɚ sˈɪstəm ɐdˈæpts tə wˈeɪtləsnəs.