Insomnia with objective short sleep duration: the most biologically severe phenotype of the disorder

Abstract

Until recently, the association of chronic insomnia with significant medical morbidity was not established and its diagnosis was based solely on subjective complaints. We present evidence that insomnia with objective short sleep duration is the most biologically severe phenotype of the disorder, as it is associated with cognitive-emotional and cortical arousal, activation of both limbs of the stress system, and a higher risk for hypertension, impaired heart rate variability, diabetes, neurocognitive impairment, and mortality. Also, it appears that objective short sleep duration is a biological marker of genetic predisposition to chronic insomnia. In contrast, insomnia with objective normal sleep duration is associated with cognitive-emotional and cortical arousal and sleep misperception but not with signs of activation of both limbs of the stress system or medical complications. Furthermore, the first phenotype is associated with unremitting course, whereas the latter is more likely to remit. We propose that short sleep duration in insomnia is a reliable marker of the biological severity and medical impact of the disorder. Objective measures of sleep obtained in the home environment of the patient would become part of the routine assessment of insomnia patients in a clinician's office setting. We speculate that insomnia with objective short sleep duration has primarily biological roots and may respond better to biological treatments, whereas insomnia with objective normal sleep duration has primarily psychological roots and may respond better to psychological interventions alone.

Copyright © 2012 Elsevier Ltd. All rights reserved.

Figures

Figure 1. The 24-hour plasma ACTH (top) and cortisol (bottom) concentrations in insomnia patients (■) and controls (○)

The thick black line on the abscissa indicates the sleep recording period. Error bar indicates standard error (SE). *P

Figure 2. The 24-hour circadian secretory pattern of cortisol in insomnia patients with short total sleep time (□) and longer total sleep time (●)

The thick black line on the abscissa indicates the sleep recording period. Error bar indicates SE. *P

Figure 3. Multivariable Adjusted Odds Ratio of Hypertension associated with Insomnia with Objective Short Sleep Duration

Data are presented as OR, in bold, and 95%CI, in parentheses. Based on findings by Vgontzas et al

Figure 4. Multivariable Adjusted Odds Ratio of Diabetes associated with Insomnia with Objective Short Sleep Duration

Data are presented as OR, in bold, and 95%CI, in parentheses. Based on findings by Vgontzas et al

Figure 5. Insomnia with Objective Short Sleep Duration is associated with Deficits in the Executive Control of Attention

Modified from Rios et al, based on findings by Fernandez- Mendoza et al and others,,,–

Figure 6. Multivariable Adjusted Odds Ratio of Mortality associated with Insomnia with Objective Short Sleep Duration in Men

Data are presented as OR, in bold, and 95%CI, in parentheses. Based on findings by Vgontzas et al

Figure 7. Sleep Misperception in Insomnia: Role of Objective Sleep Duration and Psychological Profiles

Panel A: data are presented as mean, in bold, and SE, in parentheses. Panel B: data are presented as mean T scores in each clinical and content scale (for the sake of simplicity SE have been omitted); 1-HS = hypochondriasis, 2-D = depression, 3-HY = hysteria, 4-PD = psychopathic deviate, 6-PA = paranoia, 7-PT = psychasthenia, 8-SC = schizophrenia, 9- MA = hypomania, 0-SI, social introversion, DEP = depression, ANX = anxiety, and ES = ego strength. Insomnia

Figure 8. Heuristic model of the underlying pathophysiological mechanisms and clinical characteristics of the two insomnia phenotypes based on objective sleep duration

The common characteristics of the two phenotypes are presented in the overlapping area, while their unique characteristics are presented in the areas of each phenotype that do not overlap.