Endocrine and neurophysiological examination of sleep disorders in Williams syndrome

Background: A high rate of sleep disturbances have been reported in individuals with Williams syndrome (WS), but the underlying aetiology has yet to be identified. Melatonin and cortisol levels are known to affect and regulate sleep/wake patterns. We investigated the changing levels of these hormones in order to explore any relationship with sleep disturbances in children with WS. Methods: Twenty seven children with WS and 27 typically developing (TD) children were recruited. Sleep was monitored using actigraphy and pulse oximetry. Parents completed Children’s Sleep Habit Questionnaire (CSHQ). Saliva and first void morning urine samples were collected from the children. Saliva was collected at three time points: 4-6pm, before bedtime and first thing after awakening. Levels of salivary melatonin and cortisol were analysed by enzyme linked immunoassays. For determination of melatonin, cortisol and their metabolites in urine samples, specific Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry (UHPLC-MS/MS) method was developed. Results: CSHQ and actigraphy indicated that children with WS were significantly affected by several types of sleep disturbances, including: abnormally high sleep latency and excessive night waking. Children in WS group had shallower falls in salivary cortisol levels and less pronounced rises in salivary melatonin at bedtime compared to TD controls (p < 0.01 and p = 0.04 respectively). Furthermore, it was found that children with WS also had significantly higher levels of bedtime cortisol compared to TD controls (p = 0.03). Using UHPLC-MS/MS analysis it was shown that children with WS secrete less melatonin during the night compared to healthy controls (p < 0.01). Also, levels of cortisone, a metabolite of cortisol were significantly higher in the WS group (p = 0.05). Conclusions: We found that children with WS had significant sleep disturbances which may be associated with their increased bedtime cortisol and lower evening melatonin. Both hormones play a significant role in the circadian rhythm and sleep/wake cycle, therefore it was necessary to look closely at these endocrine markers in individuals suffering from sleep disorders. Sleep problems in children with WS may adversely affect daytime activity and the quality of life, as well as social, emotional, health and economic functioning of the entire family. Hence, finding their cause is of great importance for affected children and their families

Determination of urinary cortisol, cortisone and 6-sulfatoxymelatonin using dilute and shoot ultra-high pressure liquid chromatography-tandem mass spectrometry

Human sleep is a natural part of every individual's life. Clear relationship between sleep and endocrine system has been already established. In particular, melatonin and cortisol are known to affect and regulate sleep/wake patterns. Here we report the development of an ultra-high pressure liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for simultaneous measurement of 6-sulfatoxymelatonin (MT6s), cortisol and cortisone in urine. A separate method was developed for measurement of creatinine in urine. These levels were used to normalise the levels of analytes. First void morning urine samples were collected from 24 healthy volunteers. Samples were diluted 1:1 in water prior to injection onto reversed-phase C18 column and analysed using UHPLC-MS/MS method. Linear calibrations were obtained for all analytes with correlation coefficient in the range 0.998-0.999. The observed concentration was found to be in the range 92-105% for cortisol, 92-107% for cortisone and between 93 and 120% for MT6s of the reference levels. The total run time of 6 min with all peaks of interest eluting within 3 min was obtained. This demonstrates the feasibility of utilising the method for large multi-scale studies, where high throughput is required for studying the circadian rhythm of melatonin and cortisol secretion. These hormones play significant role in circadian rhythm and sleep/wake cycle; therefore it is important to monitor the levels of these endocrine markers in individuals suffering from sleep disorders. It is also beneficial with clinical applications to analyse melatonin and cortisol simultaneously in order to assess their interrelationships of these substances, such as their effect on diurnal rhythm and sleep

Abnormal secretion of melatonin and cortisol in relation to sleep disturbances in children with Williams syndrome

Objective: A high rate of sleep disturbances has been reported in individuals with Williams syndrome (WS) but the underlying aetiology has yet to be identified. Melatonin and cortisol levels display circa- dian rhythmicity and are known to affect and regulate sleep/wake patterns. The current study examined the levels of these two endocrine markers and explored a possible relationship with sleep patterns in children with WS. Methods: Twenty-fivechildrenwithWSand27typicallydevelopingage-andgender-matchedcompar- ison children were recruited. Saliva was collected from each child at three time points: 4–6 pm, before natural bedtime, and after awakening. The levels of salivary melatonin and cortisol were analysed by specific enzyme-linked immunoassays. Sleep patterns were examined using actigraphy and the Chil- dren’s Sleep Habit Questionnaire. Results: The WS group had shallower drops in cortisol and less pronounced increase in melatonin at bedtime compared to the controls. Furthermore, they also had significantly higher levels of cortisol before bedtime. Conclusions: Increased bedtime cortisol and less pronounced rise in melatonin levels before sleep may play a role in the occurrence of sleep disturbances, such as delayed sleep onset, observed in children with WS. As both markers play a significant role in our circadian rhythm and sleep/wake cycle, it is neces- sary to examine sleep using multi-system analysis