Citation

Carskadon MA, Sharkey KM, Knopik VS, McGeary JE. Sleep 2012; 35(6): 791-796.

Affiliation

Department of Psychiatry and Human Behavior, Alpert Medical School of Brown University, Providence, RI, USA. Mary_Carskadon@brown.edu

Comment In:

Sleep 2012;35(6):739-40.

Copyright

(Copyright © 2012, American Academy of Sleep Medicine, Publisher Associated Professional Sleep Societies)

DOI

10.5665/sleep.1876

PMID

22654198

PMCID

PMC3353054

Abstract

OBJECTIVES: This study examined whether the 5-HTTLPR polymorphism in the SLC6A4 gene is associated with self-reported symptoms of depressed mood in first-year university students with a persistent pattern of short sleep. DESIGN: Students provided DNA samples and completed on-line sleep diaries and a mood scale during the first semester. A priori phenotypes for nocturnal sleep and mood scores were compared for the distribution of genotypes. SETTING: Brown University, Providence, Rhode Island. PARTICIPANTS: A sample of 135 first-year students, 54 male, 71 Caucasian, mean age 18.1 (± 0.5) yr. INTERVENTIONS: None. MEASUREMENTS: Students completed on-line sleep diaries daily across the first term (21-64 days; mean = 51 days ± 11) and Center for Epidemiologic Studies-Depression (CES-D) mood scale after 8 wk. DNA was genotyped for the triallelic 5-HTTLPR polymorphism. Low-expressing S and L(G)polymorphisms were designated S', and high-expressing L(A) was designated L'. Phenotype groups were identified from a combination of CES-D (median split: high > 12; low < 13) and mean nocturnal total sleep time (TST) from diaries: (shorter ≤ 7 hr; longer ≥ 7.5 hr). Three genotypes were identified (S'S', S'L', L'L'); the S'S' genotype was present in a higher proportion of Asian than non-Asian students. RESULTS: FOUR PHENOTYPE GROUPS WERE COMPARED: 40 students with shorter TST/high CES-D; 34 with shorter TST/low CES-D; 29 with longer TST/high CES-D; 32 with longer TST/low CES-D. Female:male distribution did not vary across phenotype groups (chi-square = 1.39; df = 3; P = 0.71). S'S' participants (n = 23) were overrepresented in the shorter TST/high CES-D group (chi- square = 15.04; df = 6; P < 0.02). This association was sustained after removing participants with preexisting evidence of depressed mood (chi-square = 12.90; df = 6; P = 0.045). CONCLUSION: These data indicate that young adults who reported shorter nocturnal sleep and higher depressed mood are more likely than others to carry a variant of the SLC6A4 gene associated with low expression of the serotonin transporter.

Language: en