Chronobiology international
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Comparative Study
Correlations between objective and subjective sleep and circadian markers in remitted patients with bipolar disorder.
Bipolar disorder (BD) is a chronic psychiatric condition characterized by recurrences of depressive and (hypo)manic episodes. Patients in remission report a wide range of sleep and circadian disturbances that correlate with several outcomes measures such as functioning or physical health. The most appropriate way to measure these abnormalities in clinical practice requires further investigation since the external validity of self-reports, as compared to more physiological measures (such as polysomnography or actigraphy), has been questioned. ⋯ No correlation was observed between markers for the amplitude of rhythms. While the external validity of the CTI clearly requires further investigation, this study supported the external validity of the CSM and the PSQI for phase preference, sleep duration and latency. We conclude that the CSM and the PSQI could be useful in routine practice and research when actigraphy is not easily available.
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Accumulating evidence suggests that dopamine plays a key role in sleep-wake regulation. Cerebral dopamine levels are regulated primarily by the dopamine transporter (DAT) in the striatum and by catechol-O-methyl-transferase (COMT) in the prefrontal cortex. We hypothesized that the variable-number-tandem-repeat (VNTR) polymorphism in the 3'-untranslated region of the gene encoding DAT (DAT1, SLC6A3; rs28363170) and the Val158Met polymorphism of COMT (rs4680) differently affect actigraphy-derived rest-activity cycles and sleep estimates in healthy adults (65 men; 45 women; age range: 19-35 years). ⋯ Moreover, whereas the proportion of women among the genotype groups did not differ, COMT genotype affected body-mass-index (BMI), such that Val/Met individuals had lower BMI than the homozygous genotypes (p < 0.04). While awaiting independent replication and confirmation, our data support an association of genetically-determined differences in cerebral dopaminergic neurotransmission with daytime sleepiness and individual rest-activity profiles, as well as other sleep-associated health characteristics such as the regulation of BMI. The differential associations of DAT1 and COMT polymorphisms may reflect the distinct local expression of the encoded proteins in the brain.