Table 1.
Studies of melatonin levels in individuals with autism.
| Study | Sample | Study group | Measured variable | Results |
|---|---|---|---|---|
| Ritvo et al. (21) | Urine | Young adults with autism (N = 10) | Melatonin concentration | Increased daytime values compared to typically developing controls |
| Similar nighttime values compared to typically developing controls | ||||
| Nir et al. (22) | Serum | Young men with autism (N = 10) | Melatonin concentration | Increased daytime values compared to typically developing controls |
| Decreased nighttime values compared to typically developing controls | ||||
| Kulman et al. (19) | Serum | Children with autism (N = 14) | Melatonin concentration (24-h circadian rhythm) | Decreased nighttime values compared to typically developing controls |
| No circadian variation in 10/14 (71.4%) children with autism | ||||
| Inverted rhythm in 4/14 (28.6%) children with autism | ||||
| Tordjman et al. (23) | Urine | Children and adolescents with autism (N = 49) | 6-Sulphatoxymelatonin excretion rate (12-h collection) | Decreased nighttime values compared to typically developing controls |
| Melke et al. (24) | Plasma | Adolescents and young adults with autism (N = 43) | Melatonin concentration | Decreased daytime values compared to typically developing controls |
| Mulder et al. (25) | Urine | Children and adolescents with autism (N = 20) | 6-Sulphatoxymelatonin excretion rate (24-h collection) | Trend to lower 24-h melatonin excretion rate in hyperserotonemic compared to normoserotonemic individuals with autism |
| Tordjman et al. (18) | Urine | Post-pubertal adolescents and young adults with autism (N = 43) | 6-Sulphatoxymelatonin excretion rate (split 24-h collection) | Decreased daytime values compared to typically developing controls |
| Decreased nighttime values compared to typically developing controls | ||||
| No circadian variation in 10/43 (23.2%) individuals with autism |