Date Published: July 26, 2017
Publisher: Public Library of Science
Author(s): Anna F. Johann, Elisabeth Hertenstein, Simon D. Kyle, Chiara Baglioni, Bernd Feige, Christoph Nissen, Alastair J. McGinness, Dieter Riemann, Kai Spiegelhalder, Andrea Romigi.
To replicate the association between insomnia with objective short sleep duration and hypertension, type 2 diabetes and duration of insomnia.
Retrospective case-control study.
Department of Psychiatry and Psychotherapy, Medical Center—University of Freiburg.
328 patients with primary insomnia classified according to DSM-IV criteria (125 males, 203 females, 44.3 ± 12.2 years).
All participants were investigated using polysomnography, blood pressure measurements, and fasting routine laboratory.
Insomnia patients with short sleep duration (< 6 hours) in the first night of laboratory sleep presented with a longer duration of insomnia compared to those with normal sleep duration (≥ 6 hours) in the first night of laboratory sleep. Insomnia patients who were categorised as short sleepers in either night were not more likely to suffer from hypertension (systolic blood pressure of ≥ 140 mm Hg, diastolic blood pressure of ≥ 90 mm Hg, or a previously established diagnosis). Data analysis showed that insomnia patients with objective short sleep duration were not more likely to suffer from type 2 diabetes (fasting plasma glucose level of ≥ 126 mg/dl, or a previously established diagnosis). However, the diabetes analysis was only based on a very small number of diabetes cases. As a new finding, insomnia patients who were categorised as short sleepers in either night presented with increases in liver enzyme levels. The finding on insomnia duration supports the concept of two distinct sub-groups of insomnia, namely insomnia with, and without, objectively determined short sleep duration. However, our data challenges previous findings that insomnia patients with short sleep duration are more likely to suffer from hypertension.
Insomnia is one of the most frequent mental disorders [1,2] leading to clinically relevant impairment in diverse areas of health-related quality of life  as well as to high societal cost . Women have an increased risk to develop insomnia compared to men  and the prevalence of the disorder increases significantly with age . Patients with insomnia have an increased risk of developing mental disorders, especially depression [7,8]. In the last decade, a number of studies suggest that insomnia also increases the risk for cardiometabolic diseases [9,10,11].
The results of the current Freiburg Cohort corroborate previous findings  that insomnia with objective short sleep duration is characterised by a longer duration of insomnia in comparison with insomnia with normal sleep duration. In detail, those with short sleep duration in the first sleep laboratory night had a 3.7 years longer insomnia duration in comparison with those with normal sleep duration. Moreover, as a new finding, insomnia patients with objective short sleep duration appear to present with increases in liver enzyme levels. However, we did not find any support for the assumption that insomnia with objective short sleep duration is specifically associated with hypertension, a finding that has been reported in studies based on the Penn State Cohort [13,14].