Assessment of excessive sleepiness and insomnia as they relate to circadian rhythm sleep disorders.

Sleep disturbances are associated with a number of psychiatric disorders, including depression, anxiety disorders, and substance use disorders, and many psychiatric patients report symptoms such as insomnia, tiredness, fatigue, and excessive sleepiness. Despite their known negative impact on daytime functioning and quality of life, less than 10% of individuals with these symptoms visit physicians specifically for their sleeping problems. Although there are many explanations for this lack of reporting, one possibility is that individuals are often unaware of the impact of sleepiness on their daytime functioning. Therefore, the burden of identifying sleepiness and its consequences often resides with physicians and other health care professionals. This process of detection is assisted by rating scales and subjective and objective tests. Although prior discussions on these topics have focused on the understanding and identification of either excessive sleepiness or insomnia, these symptoms often coexist, introducing a clinical challenge in that it becomes unclear which of these two should become the initial focus of clinical attention. When both excessive sleepiness and insomnia coexist, a circadian rhythm sleep disorder may be present, such as jet lag type, delayed and advanced sleep phase types, and shift work type.