Table 2.

Number of published epidemiological studies on the relationship between sleep duration and body mass index (BMI) or prevalence or incidence of overweight/obesity.

	Number of studies in children		Number of studies in adults		Total number of studies
	Positive findings	Total number of studies	Positive findings	Total number of studies	Positive findings	Total number of studies
Cross-sectional  studies	13	13	21	25	34	38
Prospective  studies	4	4	4	5	8	9
All studies	7	7	25	30	42	47

References for each study can be found in the 2008 review by Patel & Hu (30) with the following additions that were not included in the Patel & Hu review. Cross-sectional studies in children: Nixon, Sleep 2008 (55) and Yu, Sleep 2007 (56). Cross-sectional studies in adults: Stranges, AJE 2008 (30); Lopez-Garcia AJCN 2008 (31), Littman et al. 2006 (negative) (32), Rontoyanni 2007 (33), Bjorvatn 2007 (34). Prospective studies in children: Lumeng et al. (40), Taveras et al. 2008 (41), prospective studies in adults: Chaput et al. 2008 (45), Stranges, AJE 2008 (30).