Efek bulan adalah sebuah dugaan korelasi yang tak terbukti antara tahap-tahap spesifik dari siklus bulan selama sekitar 29.5 hari dan perubahan perilaku dan psikologi pada makhluk-makhluk hidup di Bumi, termasuk manusia. Dalam beberapa kasus, dugaan efek dapat tergantung pada dugaan-dugaan luar, seperti sinar bulan. Dalam kasus lain, seperti perkiraan siklus bulanan menstruasi pada manusia (namun bukan mamalia lainnya), pertepatan dari waktu tak merefleksikan pengaruh bulan yang diketahui.

Sejumlah kajian menguji efek tersebut pada manusia. Pada akhir 1980an, terdapat setidaknya 40 kajian yang diterbitkan soal hubungan bulan-kegilaan,^[1] dan setidaknya 20 kajian yang diterbitkan soal hubungan bulan-tingkat kelahiran.^[2] Ini membolehkan beberapa ulasan sastra ekstensif dan meta-analisis dibuat, yang tak menemukan korelasi antara siklus bulan dan biologi atau perilaku manusia.^[1][2][3][4]

• Yonezawa, T; Uchida, M; Tomioka, M; Matsuki, N (2016). "Lunar Cycle Influences Spontaneous Delivery in Cows". PLOS ONE. 11 (8): e0161735. Bibcode:2016PLoSO..1161735Y. doi:10.1371/journal.pone.0161735. PMC 5006988. PMID 27580019. Pemeliharaan CS1: DOI bebas tanpa ditandai (link)

• Abell, George (1979). Review of the book The Alleged Lunar Effect by Arnold Lieber, Skeptical Inquirer, Spring 1979, 68–73. Reprinted in Science Confronts the Paranormal, edited by Kendrick Frazier, Prometheus Books, ISBN 0-87975-314-5.
• Abell, George and Barry Singer (1981). Science and the Paranormal - probing the existence of the supernatural, Charles Scribner's Sons, chapter 5, ISBN 0-684-17820-6.
• Berman, Bob (2003). Fooled by the Full Moon - Scientists search for the sober truth behind some loony ideas, Discover, September 2003, page 30.
• Caton, Dan (2001). Natality and the Moon Revisited: Do Birth Rates Depend on the Phase of the Moon?, Bulletin of the American Astronomical Society, Vol 33, No. 4, 2001, p. 1371. A summary of the results of the paper.
• Diefendorf, David (2007), Amazing... But false! Hundreds of "facts" you thought were true, but aren't, Sterling Publishing, ISBN 978-1-4027-3791-6
• Foster, Russell G.; Roenneberg, Till (2008). "Human Responses to the Geophysical Daily, Annual and Lunar Cycles". Current Biology. 18 (17): R784 – R794. doi:10.1016/j.cub.2008.07.003. PMID 18786384. S2CID 15429616. Lunar cycles had, and continue to have, an influence upon human culture, though despite a persistent belief that our mental health and other behaviours are modulated by the phase of the moon, there is no solid evidence that human biology is in any way regulated by the lunar cycle
• Packer, C.; Swanson, A.; Ikanda, D.; Kushnir, H. (2011). "Fear of Darkness, the Full Moon and the Nocturnal Ecology of African Lions". PLOS ONE. 6 (7): 22285. Bibcode:2011PLoSO...622285P. doi:10.1371/journal.pone.0022285. PMC 3140494. PMID 21799812. Pemeliharaan CS1: DOI bebas tanpa ditandai (link)
• Palmer, JD; Udry, JR; Morris, NM (1982). "Diurnal and weekly, but no lunar rhythms in humans copulation". Human Biology; an International Record of Research. 54 (1): 111–21. PMID 7200945.
• Sanduleak, Nicholas (1985). The Moon is Acquitted of Murder in Cleveland, Skeptical Inquirer, Spring 1985, 236–42. Reprinted in Science Confronts the Paranormal, edited by Kendrick Frazier, Prometheus Books, ISBN 0-87975-314-5.
• Zimecki, Michał (2006). "The lunar cycle: effects on human and animal behavior and physiology". Postepy Higieny I Medycyny Doswiadczalnej. 60: 1–7. PMID 16407788. Diarsipkan dari asli tanggal 2017-06-26. Diakses tanggal 2021-07-20. In fish the lunar clock influences reproduction and involves the hypothalamus-pituitary-gonadal axis. In birds, the daily variations in melatonin and corticosterone disappear during full-moon days. The lunar cycle also exerts effects on laboratory rats with regard to taste sensitivity and the ultrastructure of pineal gland cells. Cyclic variations related to the moon's phases in the magnitude of the humoral immune response of mice to polivinylpyrrolidone and sheep erythrocytes were also described. It is suggested that melatonin and endogenous steroids may mediate the described cyclic alterations of physiological processes. The release of neurohormones may be triggered by the electromagnetic radiation and/or the gravitational pull of the moon

• The Skeptic's Dictionary on the lunar effect
• Madness and the Moon
• Lunar Rhythms in Aquatic Animals A General Review
• Moon Phase Meaning (A study of nocturnal activity of native Australian mammals and moon phase)