The burden of heat-related mortality attributable to recent human-induced climate change.

Climate change affects human health; however, there have been no large-scale, systematic efforts to quantify the heat-related human health impacts that have already occurred due to climate change. Here, we use empirical data from 732 locations in 43 countries to estimate the mortality burdens associated with the additional heat exposure that has resulted from recent human-induced warming, during the period 1991-2018. Across all study countries, we find that 37.0% (range 20.5-76.3%) of warm-season heat-related deaths can be attributed to anthropogenic climate change and that increased mortality is evident on every continent. Burdens varied geographically but were of the order of dozens to hundreds of deaths per year in many locations. Our findings support the urgent need for more ambitious mitigation and adaptation strategies to minimize the public health impacts of climate change.

Interaction between sleep and growth hormone. Evaluated by manual polysomnography and automatic power spectrum analysis.

The relation between nightly growth hormone (GH) secretion and sleep is poorly understood. To examine whether disturbances in GH secretion are reflected in abnormal sleep patterns 8 subjects with isolated GH deficiency and 9 subjects with excess of GH (acromegalics) underwent all night sleep studies, polysomnography. Moreover, the effect of correcting GH concentration on sleep patterns were examined in the same subjects. The results showed that all subjects with GH disturbances had abnormal REM and delta sleep and normalization of GH concentration was followed by correction of the sleep stages. By power spectrum analysis of the sleep EEG it was showed that during low GH concentration the sleep energy was low, and high GH concentration was associated with high sleep energy, and correction of abnormal plasma GH levels resulted in normalization of REM and delta sleep energy per time unit.

[Effect of growth hormone on sleep energy]. / Vaeksthormonets indvirkning på søvnenergien.

The purpose of the study was to examine REM and delta sleep energy in adults with high and normal plasma growth hormone (GH) concentration by means of power spectrum EEG analysis. After a three-day regular sleep/waking schedule, all-night polysomnographic recordings were performed on two consecutive nights before as well as one year after treatment for acromegaly by adenomectomy. The sleep energy was calculated by power spectrum analysis. We studied nine patients aged 24-45 years with untreated active acromegaly. The same patients were re-examined one year after adenomectomy when plasma GH concentrations were normal. The acromegaly was verified biochemically by measuring basal plasma GH concentration and plasma GH during hyperglycaemia as well as insulin-like growth factor. Cerebral computer tomography (CT) and magnetic resonance (MR) scans revealed an intrasellar adenoma in all patients. The resulting sleep records obtained before and after adenomectomy were subjected to power spectrum analysis and a manually blinded sleep scoring. The power spectrum analysis showed that when circulating GH was elevated the energy in the REM sleep per minute was significantly higher compared to the REM energy/min after surgery when GH concentrations had normalized. A similar relation was found for delta sleep (stage three and four, deep sleep) where the energy per minute was higher before treatment than after. The study demonstrates that plasma GH concentration was correlated to sleep energy. During high GH concentration the REM and delta sleep energies were high and normalization of plasma GH was followed by normalization of REM and delta sleep energy per time unit.

Relationship of age to power spectrum analysis of EEG during sleep.

We describe a method of power spectrum analysis of all-night sleep EEGs in 20 normal subjects aged 18-43 years. The analysis calculates the energy of the whole sleep period, the various frequency bands, and selected sleep stages automatically. The numerical value of the energies was directly comparable between subjects, presented in numbers (microV2s) and displayed as a color density spectral array with fixed power values for each color. A significant relationship between age and power spectra was found, in that total energy/minute was higher in younger subjects than in older. The energy in delta sleep/minute also showed an inverse relationship with age.

Effect of growth hormone on human sleep energy.

OBJECTIVE: We wished, by means of power spectrum EEG analysis, to examine REM and delta sleep energy in adults with high and normal plasma growth hormone (GH) concentration. DESIGN: After a 3-day regular sleep/wake schedule, all-night polysomnographic recordings were performed on two consecutive nights before as well as one year after treatment for acromegaly by adenomectomy. The sleep energy was calculated by power spectrum analysis. PATIENTS: We studied nine patients aged 24-45 years with untreated active acromegaly. The same patients were reexamined one year after adenomectomy when plasma GH concentrations were normal. MEASUREMENTS: The acromegaly was verified biochemically by measuring basal plasma GH concentration and plasma GH during hyperglycaemia as well as insulin-like growth factor. Cerebral computer tomography (CT) and magnetic resonance (MR) scans revealed an intrasellar adenoma in all patients. The resulting sleep records obtained before and after adenomectomy were subjected to power spectrum analysis and a manually blinded sleep scoring. RESULTS: The power spectrum analysis showed that when circulating GH was elevated the energy in the REM sleep per minute was significantly higher compared to the REM energy/min after surgery when GH concentration had normalized. A similar relation was found for delta sleep (stage 3 + 4, deep sleep) where the energy per minute was higher before treatment than after. CONCLUSIONS: The study demonstrates that plasma GH concentration was correlated to sleep energy. During high GH concentration the REM and delta sleep energy were high and normalization of plasma GH was followed by normalization of REM and delta sleep energy per time unit.

Sleep in acromegaly before and after treatment with adenomectomy.

Daytime somnolence and fatigue are frequently ignored symptoms in acromegaly. To examine whether sleep apnea or other abnormalities in the sleep structure is the underlying cause, 9 young patients with active untreated acromegaly for 2-7 years were studied with all night polysomnography. It revealed a decrease in REM sleep time in all the acromegalics compared to age- and sex-matched normal subjects (p less than 0.001) and also a reduction in delta sleep (p less than 0.05). None had obstructive sleep apnea. At reexamination 12-15 months posttreatment the daytime sleepiness had disappeared in all patients. REM sleep time increased in all patients (p less than 0.001) to normal level; delta sleep time increased moderately (p less than 0.05). Thus sleepiness in patients with high fasting level of growth hormone (GH) is not related to sleep apnea but more likely to a reduced amount of REM sleep time. By normalizing the GH concentration, REM sleep time became normal and the daytime sleepiness disappeared in all patients.

The influence of growth hormone on sleep in adults with growth hormone deficiency.

Eight patients with isolated growth hormone deficiency (IGHD), 20-30 years old were studied with polysomnography before and after 6 months of treatment with growth hormone (GH). During GH treatment total sleep time decreased and REM sleep time increased significantly. Delta sleep time (stage 3 + 4) did not change significantly. All patients reported improved well-being and none wished to discontinue the treatment with growth hormone. These findings suggest that GH has an effect on sleep. The effect of increased REM sleep in humans is incompletely understood, but sleep recordings may be one way of directly monitoring the effect of GH on the central nervous system.

Growth hormone-deficient young adults have decreased deep sleep.

The sleep in young adults with severe isolated growth hormone deficiency (IGHD) was examined by polysomnography. There was a significant decrease in delta sleep time (= stages 3 + 4, slow wave sleep, 'deep sleep'), especially in stage 4. The total sleep time was significantly increased compared to age- and sex-matched normal subjects. The increase in total sleep time was related to an increase in stage 1 and stage 2 sleep. There was no significant difference in total rapid eye movement (REM) sleep time, but when correcting for the very long sleep time in the IGHD subjects, the cumulated REM time within the first 390 min of sleep was significantly less than in the normal subjects.

Decrease in delta sleep in growth hormone deficiency assessed by a new power spectrum analysis.

Seven pituitary dwarfs between 18 and 28 years old with congenital absence of growth hormone, i.e., isolated growth hormone deficiency (IGHD), were examined with polysomnography. Power spectrum analyses of the delta band showed a significant decrease in power in the delta sleep in the IGHD patients compared with the controls. Power spectrum analyses add a new dimension to the description of sleep, as it evaluates, not only frequency of the electroencephalogram (EEG) in time but also the amplitude of the EEG signal. This means that sleep of same quantity can have different powers; for example, 15 min of stage 4 in one person can have another quality than 15 min of stage 4 in another person. An additional observation was that the power in the delta band in the normal young controls showed a correlation to age, with significant decrease within a 10-year period.

Sleep disturbances in torture survivors.

One of the main complaints in torture survivors is sleep disturbance with nightmares, too little sleep and daytime fatigue. Seven subjects, who had been exposed to torture from 6 months to seven years previously, were examined by polysomnography. All had abnormal sleep patterns compared with normal age- and sex-matched controls. The subjects woke frequently from REM sleep, had reduced REM sleep duration, absent Stage 4 sleep, short total sleep time and low sleep efficiency. This study revealed that previously healthy young persons subjected to extreme stress may develop an abnormal sleep pattern.