[Sleep-wake cycle in chemotherapy patients: a retrospective study].
Over 50% of cancer patients suffer from insomnia, nearly twice the estimated prevalence in the general population. However, this widespread problem has received far less attention compared to cancer pain and fatigue. The aim of this study was to determine whether certain factors can alter the sleep-wake cycle in this patient subgroup and whether altered nyctohemeral sleep rhythms may negatively impact on quality of life. The medical records of 101 patients treated at the Cancer Center, San Giovanni Battista Hospital, Turin, and who had died of cancer in 2007, were reviewed. Extracted from each record were data on: patient age, sex, primary tumor site, presence of pain, concomitant conditions, concomitant medications, type of therapy, chemotherapeutic (CT) scheme, survival, and side effects. The sample was divided into two subgroups defined as inducers or non-inducers, depending on whether the patient had taken medications or not to treat insomnia. Significant differences between the two groups for these variables were tested using statistical analysis. A statistically significant difference between the two groups emerged for anxiety-depression syndromes (P=0.00001), the number of sleeping pills taken in association with a concurrent anxiety-depression syndrome (P=0.01463), and side effects (P=0.0015). There was a statistically significant difference between the inducer and the non-inducer groups for female sex (one-tailed Fisher's exact test; P=0.04170) but the difference was marginal on Fisher's two-tailed test (P=0.06121). No statistically significant differences between the two groups were found for mean age (P=0.61281), median age (P=0.9996), primary tumor site, concomitant conditions (P=0.4205), survival (P=0.5704), presence of pain (P=0.53300) or type of therapy (P=0.6466). Sleep disturbances are a common complaint of cancer patients but have only recently attracted greater attention as the diagnosis of cancer has increased. Sleep disturbances are not an isolated problem but rather lead to a vicious circle of insomnia and fatigue where it is not always possible to distinguish between cause and effect. Future studies are needed to gain insight into the underlying mechanisms and a better understanding of what causes alterations in circadian rhythm.