Non-alcoholic fatty liver disease and sleep disorders

Table 1 Correlations between non-alcoholic fatty liver disease and sleep disorders

Items		Correlations
Sleep	Sleep duration	Short sleep duration and long daytime naps are risk factors for NAFLD[19-22]
		Moderate sleep duration reduces the risk of NAFLD[23-26]
		Excessive sleep duration increases the risk of NAFLD[23,25,30,31]
	Sleep quality	Poor sleep quality was significantly associated with an increased risk of NAFLD[19,25]
Sleep disorders	Insomnia and daytime sleepiness	Increases the risk of NAFLD in participants with insomnia or daytime sleepiness[35,38,39]
	Sleep-wake disturbance	Raises the risk of NAFLD through obesity, IR, disorder of glucose-lipid metabolism and inflammation[40,42-45]

NAFLD: Non-alcoholic fatty liver disease; IR: Insulin resistance.

Table 2 Selected studies investigating associations between sleep disorders and non-alcoholic fatty liver disease

Confounders	OR/HR (95%CI)	OR/HR (95%CI) adjustments for BMI	Ref.
Age, Alcohol, Smoking, Physical activity, Blood pressure, BMI, Marriage, Education level, Presence of job, Loud snoring, and Sleep apnea	M 1.28 (1.13-1.44)	M 1.03 (0.90-1.19)	Kim et al[19], 2013
	W 1.71 (1.38-2.13)	W 1.59 (1.23-2.05)
Age, BMI, METs, and IR	1.31 (1.10-1.56)	1.29 (1.04-1.60)	Peng et al[20], 2017
Age, BMI, Alcohol, Smoking, ALT, HDL-C, TG, Diabetes, Blood pressure, Physical activity	M 1.39 (1.13-1.72)	M 2.57 (1.88-3.52)	Okamura et al[21], 2019
	W 1.46 (1.05-2.04)	W 9.38 (5.84-15.1)
Age, BMI, Smoking and Physical activity	M 0.98 (0.62-1.54)	M 1.18 (0.67-2.08)	Imaizumi et al[23], 2015
	W 1.44 (1.06-1.96)	W 1.38 (0.95-2.01)
Age, Sex, BMI, Smoking, Adiponectin, and TNF-α	1.66 (Not available)	1.62 (Not available)	Katsagoni et al[26], 2017
Age, Sex, BMI, HDL, Smoking, and Physical activity	2.230 (1.304-3.813)	1.462 (1.029-2.077)	Kim et al[31], 2019
Age, Smoking, BMI and Physical activity	1.13 (0.58–2.19)	0.93 (0.41–2.10)	Takahashi et al[29], 2020
BMI, Salt intake, Physical activity, and MetS	2.83 (2.63-3.05)	1.64 (1.35-2.00)	Wang et al[50], 2020
BMI and Abdominal obesity	2.42 (2.36-2.48)	1.21 (1.17-1.26)	Chung et al[51], 2021
BMI, Abdominal obesity, METs, and IR	4.89 (3.08–5.98)	1.78 (1.11–6.82)	Nobili et al[79], 2014
Sex, Age, BMI, IR and METs	4.20 (1.88-9.37)	3.85 (1.35-10.94)	Fu et al[55], 2022
BMI and Abdominal obesity	1.45 (1.03-1.98)	1.22 (1.02-1.45)	Krolow et al[62], 2021

ALT: Alanine aminotransferase; BMI: Body mass index; OR: Odds ratio; HR: Hazard ratio; CI: Confidence interval; TG: Triglycerides; HDL-C: High density lipoprotein-cholesterol; METs: Metabolic syndrome; IR: Insulin resistance; TNF-α: Tumor necrosis factor-α; W: Women; M: Men.