Sleep homeostasis in primary insomnia

Three main factors, hyperarousal, circadian dysrhythmia, and homeostatic dysregulation, are thought to underlie chronic insomnia. To date, most of the empirical work has focused on the issue of hyperarousal and very little work has been undertaken on the issue of steep homeostasis. In the present paper, we review the five lines of evidence which may be used to support the proposition that steep homeostasis is altered in Primary Insomnia. These include findings pertaining to Stow Wave Steep density, level of daytime sleepiness, sleepiness following steep deprivation, recovery steep following steep deprivation, and response to steep restriction therapy. In addition, we provide a discussion regarding how hyperarousal and circadian factors may interact with altered steep homeostasis, and suggestions for further inquiry. (C) 2005 Elsevier Ltd. All rights reserved.