Sleep quality may play a role in the
course of bipolar disorder, with shorter total sleep time (TST) and
increased sleep variability (SV) both associated with symptom severity,
conclude a team of US researchers.
Previous studies have indicated
that bipolar disorder patients have a reduced need for sleep during
manic episodes, and either insomnia or hypersomnia during depressive
episodes. Furthermore, 70% of euthymic patients have clinically
significant levels of sleep disturbance.
To determine the possible
role of sleep quality in bipolar disorder, June Gruber, from Yale
University in New Haven, Connecticut, and colleagues examined baseline
TST and SV data, along with symptom severity and functioning, in 468
bipolar disorder patients taking part in the National Institute of
Mental Health Systematic Treatment Enhancement Program for Bipolar
Disorder. Follow-up data was also available for 196 patients.
baseline, age was weakly but significantly negatively correlated with
TST, which was also negatively correlated with illness duration and age
at onset, indicating that patients with an earlier age at onset and a
longer illness duration slept less well and more variably.
TST was significantly associated with increased mania severity scores,
while greater SV was significantly associated with increased mania and
depression severity scores. There was no significant association between
either sleep marker and global functioning.
Consistent with these findings, the researchers reports in the Journal of Affective Disorders
that, at 12 months, shorter TST was linked to increased mania severity,
while increased SV was linked to increased mania and depression
They conclude: "The present findings represent an
important initial step towards identifying aspects of sleep functioning
that may contribute to clinical impairment in bipolar disorder.
this research underscores the importance of incorporating interventions
that target sleep functioning aimed at promoting illness
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