Association of serum BDNF levels and the BDNF Val66Met polymorphism with the sleep pattern in healthy young adults

BACKGROUND: Brain-derived neurotrophic factor (BDNF) is widely expressed in the brain and plays an important role in neuronal maintenance, plasticity, and neurogenesis. Prior studies have found that decreased serum BDNF levels are associated with perceived stress, depression, or sleep disturbances in humans. STUDY OBJECTIVES: To elucidate whether the serum BDNF levels and BDNF genotype were associated with the sleep pattern in healthy young adults. METHODS: The study group consisted of 79 healthy paid volunteers (45 men, 34 women) aged 20 to 29 years. Serum BDNF levels were measured with an enzyme-linked immunosorbent assay, and a single-nucleotide polymorphism (Val66Met) in the BDNF gene was assessed with a TaqMan assay. Details of the sleep pattern were obtained from 1-week sleep/wake records. RESULTS: Serum BDNF levels were significantly associated with sleep parameters on weekends, whereas no such association was found on weekdays. On weekends, longer total sleep time and time in bed, and later mid-sleep time were associated with lower serum BDNF levels. The difference between mid-sleep time on weekdays and that on weekends, otherwise known as social jetlag, was negatively associated with serum BDNF levels. Met/Met homozygotes of the BDNF Val66Met polymorphism had significantly longer time in bed on weekends than Val/Val homozygotes. Heterozygotes did not differ from Val/Val homozygotes. CONCLUSIONS: We first found that serum BDNF levels and the BDNF Val66Met polymorphism in healthy young adults were associated with the sleep pattern on weekends but not with that on weekdays, suggesting that the systems involved in BDNF control may be linked to endogenous sleep characteristics rather than the socially constrained sleep schedule in healthy young adults.