Methodology & Sources
How we decide what goes in the app — and how you can check it.
Quit Science is built on the published medical literature. Every recovery milestone and myth-bust is graded for how strong the evidence is and, wherever a specific claim is made, linked to the original study. This page explains the grading system, the principles behind it, and lists all 60 peer-reviewed sources in one place.
How we grade evidence
Every milestone carries one of three labels so you can weigh it appropriately. We'd rather tell you a claim is preliminary than dress it up as settled science.
Supported by systematic reviews, meta-analyses, randomized trials, or large prospective cohorts. The direction and rough timing of the effect are settled in the literature.
Supported by smaller human studies, consistent observational data, or well-understood physiology — but exact timelines vary between people and some findings are still being replicated.
Based on early, limited, or mechanistic evidence. Plausible and directionally supported, but the magnitude and timing carry real uncertainty. Treated as informative, not definitive.
Our sourcing principles
Peer-reviewed first
Recovery claims are tied to published studies in the medical literature — journals like Nature Communications, NEJM, The Lancet, BMJ, PNAS, and JACC — not blogs, marketing copy, or anecdote.
Human studies prioritized
Where human data exists, we cite it over animal or in-vitro work. Mechanistic and animal findings are used only to explain the "why," and are flagged as lower-evidence.
Every claim is traceable
Milestones and myth-busts carry inline citations that link straight to the DOI, PubMed, or PMC record. Nothing here is meant to be taken on faith — you can read the primary source.
Ranges, not false precision
Recovery timing varies with how much and how long you drank, genetics, and overall health. We show typical windows and grade our confidence rather than promising exact dates.
Honest about uncertainty
When the evidence is mixed or early, we say so — and we bust over-optimistic myths (like "the liver fully regenerates in 30 days") rather than repeat them.
Reference library
The 60 peer-reviewed sources behind our milestone and myth content. Each links to the published record so you can read it yourself.
- 1.
Antons S, Engel J, Briken P, Krüger THC, Brand M, Stark R. Treatments and interventions for compulsive sexual behavior disorder with a focus on problematic pornography use: A preregistered systematic review. Journal of Behavioral Addictions. 2022;11(3):643-666.
- 2.
Aubin HJ, Farley A, Lycett D, Lahmek P, Aveyard P. Weight gain in smokers after quitting cigarettes: meta-analysis. BMJ. 2012;345:e4439.
- 3.
Bagnardi V, Rota M, Botteri E, et al. Alcohol consumption and site-specific cancer risk: a comprehensive dose-response meta-analysis. British Journal of Cancer. 2015;112(3):580-593.
- 4.
Baker TB, Piper ME, McCarthy DE, et al. Time to first cigarette in the morning as an index of ability to quit smoking: implications for nicotine dependence. Nicotine & Tobacco Research. 2007;9(Suppl 4):S555-S570.
- 5.
Benowitz NL, Hukkanen J, Jacob P 3rd. Nicotine chemistry, metabolism, kinetics and biomarkers. Handbook of Experimental Pharmacology. 2009;(192):29-60.
- 6.
Bishehsari F, Magno E, Swanson G, et al. Alcohol and Gut-Derived Inflammation. Alcohol Research: Current Reviews. 2017;38(2):163-171.
- 7.
Bőthe B, Tóth-Király I, Zsila Á, Griffiths MD, Demetrovics Z, Orosz G. The Development of the Problematic Pornography Consumption Scale (PPCS). Journal of Sex Research. 2018;55(3):395-406.
- 8.
Bowen S, Marlatt A. Surfing the urge: brief mindfulness-based intervention for college student smokers. Psychology of Addictive Behaviors. 2009;23(4):666-671.
- 9.
Clair C, Rigotti NA, Porneala B, et al. Association of smoking cessation and weight change with cardiovascular disease among adults with and without diabetes. JAMA. 2013;309(10):1014-1021.
- 10.
Cosgrove KP, Batis J, Bois F, et al. β2-Nicotinic acetylcholine receptor availability during acute and prolonged abstinence from tobacco smoking. Archives of General Psychiatry. 2009;66(6):666-676.
- 11.
Crosby JM, Twohig MP. Acceptance and Commitment Therapy for Problematic Internet Pornography Use: A Randomized Trial. Behavior Therapy. 2016;47(3):355-366.
- 12.
Daviet R, Aydogan G, Jagannathan K, et al. Associations between alcohol consumption and gray and white matter volumes in the UK Biobank. Nature Communications. 2022;13:1175.
- 13.
Doll R, Peto R, Boreham J, Sutherland I. Mortality in relation to smoking: 50 years' observations on male British doctors. BMJ. 2004;328(7455):1519.
- 14.
Duncan MS, Freiberg MS, Greevy RA Jr, Kundu S, Vasan RS, Tindle HA. Association of smoking cessation with subsequent risk of cardiovascular disease. JAMA. 2019;322(7):642-650.
- 15.
Durazzo TC, Mon A, Gazdzinski S, et al. Serial longitudinal MRI data indicate non-linear regional gray matter volume recovery in abstinent alcohol-dependent individuals. Addiction Biology. 2015;20(5):956-967.
- 16.
Ebrahim IO, Shapiro CM, Williams AJ, Fenwick PB. Alcohol and sleep I: effects on normal sleep. Alcoholism: Clinical and Experimental Research. 2013;37(4):539-549.
- 17.
Estruch R, Coca A, Rodicio JL. Effect of Alcohol Abstinence on Blood Pressure: Assessment by 24-Hour Ambulatory Blood Pressure Monitoring. Hypertension. 1999;33(2):653-657.
View sourceDOI: 10.1161/01.HYP.33.2.653 - 18.
Faber MS, Fuhr U. Time response of cytochrome P450 1A2 activity on cessation of heavy smoking. Clinical Pharmacology & Therapeutics. 2004;76(2):178-184.
- 19.
Fernandez DP, Kuss DJ, Griffiths MD. The Pornography "Rebooting" Experience: A Qualitative Analysis of Abstinence Journals on an Online Pornography Abstinence Forum. Archives of Sexual Behavior. 2021;50(2):711-728.
- 20.
Fernandez DP, Kuss DJ, Justice LV, Fernandez EF, Griffiths MD. Effects of a 7-Day Pornography Abstinence Period on Withdrawal-Related Symptoms in Regular Pornography Users: A Randomized Controlled Study. Archives of Sexual Behavior. 2023;52(4):1819-1840.
- 21.
Fernandez DP, Kuss DJ, Griffiths MD. Short-term abstinence effects across potential behavioral addictions: A systematic review. Clinical Psychology Review. 2020;76:101828.
- 22.
Frye RE, Schwartz BS, Doty RL. Dose-related effects of cigarette smoking on olfactory function. JAMA. 1990;263(9):1233-1236.
- 23.
Funayama T, Tamura Y, Takeno K, et al. Effects of alcohol abstinence on glucose metabolism in Japanese men with elevated fasting glucose: A pilot study. Scientific Reports. 2017;7:40277.
- 24.
Gapstur SM, Bouvard V, Nethan ST, et al. The IARC Perspective on Alcohol Reduction or Cessation and Cancer Risk. New England Journal of Medicine. 2023;389(26):2486-2494.
- 25.
GBD 2016 Alcohol Collaborators. Alcohol use and burden for 195 countries and territories, 1990-2016: a systematic analysis for the Global Burden of Disease Study 2016. Lancet. 2018;392(10152):1015-1035.
- 26.
Gola M, Wordecha M, Sescousse G, et al. Can Pornography be Addictive? An fMRI Study of Men Seeking Treatment for Problematic Pornography Use. Neuropsychopharmacology. 2017;42(10):2021-2031.
- 27.
Grubbs JB, Gola M. Is Pornography Use Related to Erectile Functioning? Results From Cross-Sectional and Latent Growth Curve Analyses. Journal of Sexual Medicine. 2019;16(1):111-125.
- 28.
Grubbs JB, Perry SL, Wilt JA, Reid RC. Pornography Problems Due to Moral Incongruence: An Integrative Model with a Systematic Review and Meta-Analysis. Archives of Sexual Behavior. 2019;48(2):397-415.
- 29.
Grubbs JB, Kraus SW, Perry SL. Self-reported addiction to pornography in a nationally representative sample: The roles of use habits, religiousness, and moral incongruence. Journal of Behavioral Addictions. 2019;8(1):88-93.
- 30.
Gunn C, Mackus M, Griffin C, et al. A systematic review of the next-day effects of heavy alcohol consumption on cognitive performance. Addiction. 2018;113(12):2182-2193.
- 31.
Hackshaw A, Morris JK, Boniface S, Tang JL, Milenković D. Low cigarette consumption and risk of coronary heart disease and stroke: meta-analysis of 141 cohort studies in 55 study reports. BMJ. 2018;360:j5855.
- 32.
Hartmann-Boyce J, Chepkin SC, Ye W, Bullen C, Lancaster T. Nicotine replacement therapy versus control for smoking cessation. Cochrane Database of Systematic Reviews. 2018;5:CD000146.
- 33.
Hughes JR. Effects of abstinence from tobacco: valid symptoms and time course. Nicotine & Tobacco Research. 2007;9(3):315-327.
- 34.
Inoue-Choi M, Liao LM, Reyes-Guzman C, Hartge P, Caporaso N, Freedman ND. Association of long-term, low-intensity smoking with all-cause and cause-specific mortality in the National Institutes of Health-AARP Diet and Health Study. JAMA Internal Medicine. 2017;177(1):87-95.
- 35.
Jha P, Ramasundarahettige C, Landsman V, et al. 21st-century hazards of smoking and benefits of cessation in the United States. New England Journal of Medicine. 2013;368(4):341-350.
- 36.
Jiang M, Xin J, Zou Q, Shen JW. A research on the relationship between ejaculation and serum testosterone level in men. Journal of Zhejiang University Science. 2003;4(2):236-240. Retracted 2021.
- 37.
Kenford SL, Fiore MC, Jorenby DE, Smith SS, Wetter D, Baker TB. Predicting smoking cessation: who will quit with and without the nicotine patch. JAMA. 1994;271(8):589-594.
- 38.
Kraus SW, Krueger RB, Briken P, et al. Compulsive sexual behaviour disorder in the ICD-11. World Psychiatry. 2018;17(1):109-110.
- 39.
Lally P, van Jaarsveld CHM, Potts HWW, Wardle J. How are habits formed: Modelling habit formation in the real world. European Journal of Social Psychology. 2010;40(6):998-1009.
View sourceDOI: 10.1002/ejsp.674 - 40.
Landripet I, Štulhofer A. Is Pornography Use Associated with Sexual Difficulties and Dysfunctions among Younger Heterosexual Men? Journal of Sexual Medicine. 2015;12(5):1136-1139.
- 41.
Larimer ME, Palmer RS, Marlatt GA. Relapse prevention: An overview of Marlatt's cognitive-behavioral model. Alcohol Research & Health. 1999;23(2):151-160.
- 42.
Leclercq S, Matamoros S, Cani PD, et al. Intestinal permeability, gut-bacterial dysbiosis, and behavioral markers of alcohol-dependence severity. Proceedings of the National Academy of Sciences. 2014;111(42):E4485-E4493.
- 43.
Lewczuk K, Wizła M, Glica A, Potenza MN, Lew-Starowicz M, Kraus SW. Withdrawal and tolerance as related to compulsive sexual behavior disorder and problematic pornography use — Preregistered study based on a nationally representative sample in Poland. Journal of Behavioral Addictions. 2022;11(4):979-993.
- 44.
Lindson N, Livingstone-Banks J, Butler AR, et al. Electronic cigarettes for smoking cessation. Cochrane Database of Systematic Reviews. 2025;11:CD010216.
- 45.
Lindson-Hawley N, Banting M, West R, Michie S, Shinkins B, Aveyard P. Gradual versus abrupt smoking cessation: a randomized, controlled noninferiority trial. Annals of Internal Medicine. 2016;164(9):585-592.
- 46.
Manning V, Garfield JBB, Reynolds J, et al. Recovery of neuropsychological function following abstinence from alcohol in adults diagnosed with an alcohol use disorder: Systematic review of longitudinal studies. PLoS One. 2024;19(1):e0296043.
- 47.
McRobbie H, Hajek P, Gillison F. The relationship between smoking cessation and mouth ulcers. Nicotine & Tobacco Research. 2004;6(4):655-659.
- 48.
Parrott AC. Does cigarette smoking cause stress? American Psychologist. 1999;54(10):817-820.
- 49.
Roerecke M, Kaczorowski J, Tobe SW, et al. The effect of a reduction in alcohol consumption on blood pressure: a systematic review and meta-analysis. Lancet Public Health. 2017;2(2):e108-e120.
- 50.
Sandberg A, Sköld CM, Grunewald J, Eklund A, Wheelock ÅM. Assessing recent smoking status by measuring exhaled carbon monoxide levels. PLoS One. 2011;6(12):e28864.
- 51.
Scanlon PD, Connett JE, Waller LA, et al. Smoking cessation and lung function in mild-to-moderate chronic obstructive pulmonary disease: the Lung Health Study. American Journal of Respiratory and Critical Care Medicine. 2000;161(2 Pt 1):381-390.
- 52.
Schuckit MA. Recognition and Management of Withdrawal Delirium (Delirium Tremens). New England Journal of Medicine. 2014;371(22):2109-2113.
- 53.
Shahab L, Goniewicz ML, Blount BC, et al. Nicotine, carcinogen, and toxin exposure in long-term e-cigarette and nicotine replacement therapy users: a cross-sectional study. Annals of Internal Medicine. 2017;166(6):390-400.
- 54.
Stickel F, Datz C, Hampe J, Bataller R. Pathophysiology and Management of Alcoholic Liver Disease: Update 2016. Gut and Liver. 2017;11(2):173-188.
- 55.
Suzuki T, et al. Blood Pressure After Changes in Light-to-Moderate Alcohol Consumption in Women and Men: Longitudinal Japanese Annual Checkup Analysis. Journal of the American College of Cardiology. 2025.
- 56.
Taylor G, McNeill A, Girling A, Farley A, Lindson-Hawley N, Aveyard P. Change in mental health after smoking cessation: systematic review and meta-analysis. BMJ. 2014;348:g1151.
- 57.
Tindle HA, Stevenson Duncan M, Greevy RA, et al. Lifetime smoking history and risk of lung cancer: results from the Framingham Heart Study. Journal of the National Cancer Institute. 2018;110(11):1201-1207.
- 58.
Topiwala A, Allan CL, Valkanova V, et al. Moderate alcohol consumption as risk factor for adverse brain outcomes and cognitive decline: longitudinal cohort study. BMJ. 2017;357:j2353.
- 59.
Voskoboinik A, Kalman JM, De Silva A, et al. Alcohol Abstinence in Drinkers with Atrial Fibrillation. New England Journal of Medicine. 2020;382(1):20-28.
- 60.
Willemse BW, Postma DS, Timens W, ten Hacken NH. The impact of smoking cessation on respiratory symptoms, lung function, airway hyperresponsiveness and inflammation. European Respiratory Journal. 2004;23(3):464-476.
Educational, not medical advice
This content is for education and motivation — it is not a diagnosis or a treatment plan, and it can't account for your individual health. Alcohol withdrawal can be medically dangerous for dependent drinkers; seizures and delirium tremens are real risks. If you drink heavily or daily, talk to a doctor before stopping. Always seek the advice of a qualified health professional with any questions about a medical condition.