The three genes within the suggestive peak on chromosome 1 (CRYZ, TYW3 and SLC44A5) have previously been associated with insulin resistance, inflammation, risk of type 2 diabetes, metabolism of lipids and lipoproteins, and cardiovascular disease.15, 16 These genes are consistent with the identification of regions associated with both tiredness and metabolic irregularities, and perhaps more broadly with ‘metabolic syndrome’ and ‘allostatic load’. This evidence concerns the gene CRYZ and Insulin resistance.