Effects of REM sleep and ambient temperature on hot flash-induced sleep disturbance

How openness and inquisitiveness led to a career as a sleep researcher and a broad contribution to sleep science

After describing my serendipitous discovery of sleep research as a potential career, I note how my openness and inquisitiveness led to a broad contribution to sleep science. After a PhD in biological psychology, I completed a postdoctoral fellowship in alcoholism and drug abuse. This led to my first studies on rebound insomnia. I then describe early studies on the relation of sleep continuity/sleep time to daytime sleepiness and function. This led to studies of how basal sleep time/sleepiness interacts with the effects of sedating and alerting drugs. Several collaborations led to studies on sleep and hot flashes in perimenopausal women and on sleep and acute and chronic pain.

Acute increases in physical activity and temperature are associated with hot flash experience in midlife women

OBJECTIVE

This study determined the association between acute changes in physical activity, temperature, and humidity and 24-hour subjective and objective hot flash experience.

METHODS

Data collection occurred during the cooler months of the year in Western Massachusetts (October-April). Women aged 45-55 across three menopause stages (n = 270) were instrumented with ambulatory monitors to continuously measure hot flashes, physical activity, temperature, and humidity for 24 hours. Objective hot flashes were assessed via sternal skin conductance, and subjective hot flashes were recorded by pressing an event marker and data logging. Physical activity was measured with wrist-worn accelerometers and used to define sleep and wake periods. Logistic multilevel modeling was used to examine the differences in physical activity, humidity, and temperature in the 10 minutes preceding a hot flash versus control windows when no hot flashes occurred. The odds of hot flashes were considered separately for objective and subjective hot flashes as well as for wake and sleep periods.

RESULTS

Data from 188 participants were included in the analyses. There was a significantly greater odds of a hot flash following acute increases in physical activity for objective waking hot flashes (odds ratio [OR], 1.31; 95% confidence interval [CI], 1.17-1.47; P < 0.001) and subjective waking hot flashes (OR, 1.16; 95% CI, 1.0-1.33; P = 0.03). Acute increases in the actigraphy signal were associated with significantly higher odds of having an objective (OR, 1.17; 95% CI, 1.03-1.35; P < 0.01) or subjective (OR, 1.72; 95% CI, 1.52-2.01; P < 0.001) sleeping hot flash. Increases in temperature were significantly related to the odds of subjective sleeping hot flashes only (OR, 1.38; 95% CI, 1.15-1.62; P < 0.001). There was no evidence for a relationship between humidity and odds of experiencing any hot flashes.

CONCLUSION

These results indicate that acute increases in physical activity increase the odds of hot flashes that are objectively measured and subjectively reported during waking and sleeping periods. Temperature increases were only related to subjectively reported nighttime hot flashes.

A systematic review of ambient heat and sleep in a warming climate

Climate change is elevating nighttime and daytime temperatures worldwide, affecting a broad continuum of behavioral and health outcomes. Disturbed sleep is a plausible pathway linking rising ambient temperatures with several observed adverse human responses shown to increase during hot weather. This systematic review aims to provide a comprehensive overview of the literature investigating the relationship between ambient temperature and valid sleep outcomes measured in real-world settings, globally. We show that higher outdoor or indoor temperatures are generally associated with degraded sleep quality and quantity worldwide. The negative effect of heat persists across sleep measures, and is stronger during the hottest months and days, in vulnerable populations, and the warmest regions. Although we identify opportunities to strengthen the state of the science, limited evidence of fast sleep adaptation to heat suggests rising temperatures induced by climate change and urbanization pose a planetary threat to human sleep, and therefore health, performance, and wellbeing.

The influence of habitual physical activity and sedentary behavior on objective and subjective hot flashes at midlife

OBJECTIVE

The purpose of this study was to evaluate relationships between physical activity, sedentary time, and hot flashes during both waking and sleeping periods using concurrent objective and subjective measures of hot flashes in midlife women.

METHODS

Women aged 45 to 55 years (n = 196) provided self-reported data on physical activity and underwent 24 hours of hot flash monitoring using sternal skin conductance. Participants used event marking and logs to indicate when hot flashes were perceived. Wake and sleep periods were defined by actigraphy. Mean ambient temperature and humidity were recorded during the study period. Generalized linear regression modeling was used to evaluate the effect of physical activity types and sedentary time on hot flash outcomes. Isotemporal substitution modeling was used to study the effect of replacing sedentary time with activity variables on hot flash frequency.

RESULTS

Modeled results indicated that increasing sitting by 1 hour was associated with a 7% increase in the rate of objectively measured but not subjectively reported hot flashes during sleep. Replacing 1 hour of sitting with 1 hour of vigorous activity was associated with a 100% increase in subjectively reported but not objectively measured waking hot flashes. There was little evidence for an effect of temperature or humidity on any hot flash outcome.

CONCLUSIONS

These data provide support for relations between sedentary time, physical activity, and hot flashes and highlight the importance of using objective and subjective assessments to better understand the 24-hour hot flash experience.

Sleep During Menopause

Postmenopause is defined retrospectively after 12 consecutive months of amenorrhea. It represents the end of the reproductive period and ovarian failure. A decrease in estrogen leads to several changes in the short and long term. Among the early changes, vasomotor symptoms (hot flashes) are particularly common, occurring in about 70% of women. In addition, there are changes in mood, anxiety, depression, and insomnia. Insomnia occurs in almost 60% of postmenopausal women. Psychosocial aspects may also affect sleep. Proper diagnosis may lead to adequate treatment of sleep disturbances during menopause. Hormonal or other complementary therapies can improve sleep quality.

Optimizing sleep across the menopausal transition

Women frequently experience sleep disturbances, particularly night-time awakenings, as they transition menopause and enter postmenopause. Sleep is essential for optimal functioning and health. Persistent and distressing sleep disturbances across menopause can negatively impact daytime functioning and productivity, and increase risk for mental and physical health conditions. While multiple factors can disturb sleep, two unique factors in the context of menopause are vasomotor symptoms and the changing reproductive hormone environment. Vasomotor symptoms are associated with sleep disturbances and contribute significantly to awakenings and amount of time spent awake during the night. Even after accounting for vasomotor and depressive symptoms, lower estradiol and higher follicle stimulating hormone levels, indicative of menopause, are associated with sleep disturbance, particularly awakenings, suggesting that the hormone environment may directly affect sleep. Management strategies for clinically significant menopausal sleep disturbances include cognitive behavioral therapy for insomnia, which is effective and durable in treating menopausal insomnia. Hormone therapy alleviates sleep disturbances, particularly in the presence of disruptive vasomotor symptoms. Sleep disturbances have a significant impact on women's functioning and health, and there is a need for further research of the underlying mechanisms to advance effective preventative and treatment strategies that ensure optimal health and well-being of midlife women.

Management of Menopause Symptoms and Quality of Life during the Menopause Transition

Some women experience bothersome symptoms around the time of menopause that may have a negative impact on their quality of life and prompt them to seek treatments. Menopausal hormone therapy was historically the treatment of choice. However, medical contraindications and personal preference for nonhormonal therapy have prompted the evaluation of a range of nonhormonal pharmacologic and non-pharmacologic therapies. This review provides an update focusing on the latest evidence-based approach for the management of bothersome symptoms of menopause.

Menopausal Symptoms and Sleep Quality in Women Aged 40–65 Years

The study examined the relationship between menopausal symptoms and sleep disturbances and the related influencing factors. Methods. We recruited women aged 40-65 years who attended the menopause clinic at Shanghai Jiao Tong University's Sixth People's Hospital from February 2011 to November 2019. The Menopause Rating Scale (MRS) was used to collect women's menopausal symptoms, and the Pittsburgh Sleep Quality Index (PSQI) was used to evaluate the subjects' sleep condition. We used logistic regression models to identify the relationship between menopausal symptoms and sleep quality. Results. A total of 1341 participants were recruited in this study. The most frequent three symptoms assessed by MRS were fatigue (72.9%), sleep disturbance (67%), and hot flashes with night sweats (65%). Participants' age was significantly associated with the severity of menopausal syndrome (P < 0.01). According to the PSQI sleep evaluation, 66.9 percent of participants had sleep disturbances (PSQI > 5). Logistic regression analysis revealed that women with mild, moderate, or severe menopausal syndrome had a 3-, 7-, and 17-fold increased chance of having sleep disturbances compared to women without menopausal syndrome. Conclusion. Women aged 40–65 years were found to have a significantly higher risk of menopausal syndrome and sleep disturbances.

Sleep during menopausal transition: a 10-year follow-up

Study Objectives

A 10-year observational follow-up study to evaluate the changes in sleep architecture during the menopausal transition.

Methods

Fifty-seven premenopausal women (mean age 46 years, SD 0.9) were studied at baseline and after a 10-year follow-up. At both time points, polysomnography (PSG) was performed, and the serum follicle-stimulating hormone (S-FSH) concentration was measured. Linear regression models were used to study the effects of aging and menopause (assessed as change in S-FSH) on sleep.

Results

After controlling for body mass index, vasomotor, and depressive symptoms, higher S-FSH level was associated with longer sleep latency (B 0.45, 95% confidence interval [CI]: 0.07 to 0.83). Aging of 10 years was associated with shorter sleep latency (B −46.8, 95% CI: −77.2 to −16.4), shorter latency to stage 2 sleep (B −50.6, 95% CI: −85.3 to −15.9), decreased stage 2 sleep (B −12.4, 95% CI: −21.4 to −3.4), and increased slow-wave sleep (B 12.8, 95% CI: 2.32 to 23.3) after controlling for confounding factors.

Conclusions

This study suggests that PSG measured sleep of middle-aged women does not worsen over a 10-year time span due to the menopausal transition. The observed changes seem to be rather age- than menopause-dependent.

Nocturia through the menopausal transition and beyond: a narrative review

INTRODUCTION AND HYPOTHESIS

Nocturia, defined as the act of waking to pass urine during sleeping, is a common problem in older women and is associated with significant morbidity and impairments in health-related quality of life. The aim of this review was to synthesize the current evidence regarding the incidence, impact, pathophysiology, and specific diagnostic approach of nocturia in the postmenopausal population.

METHODS

We searched PubMed and Web of Science databases to identify relevant studies published through June 2020. Reference lists of the reviews obtained were screened for other articles deemed pertinent by the authors.

RESULTS

Genitourinary symptoms attributed to the menopause have been reported to occur in nearly 90% of postmenopausal women, and nocturia is one of the most common. The relative deficiency in endogenous estrogen production after the menopause is thought to exacerbate all major pathophysiological mechanisms that may underlie nocturia, including reduced bladder capacity, nocturnal polyuria, global polyuria, and sleep disorders. Diminished estrogen may induce anatomical and physiological bladder changes, contributing to a reduction in functional bladder capacity. Excess nocturnal urine production can also be provoked by estrogen depletion, either via free water-predominant diuresis by an impaired secretion of antidiuretic hormone, or a salt-predominant diuresis owing to diminished activation of the renin-angiotensin-aldosterone axis. Additionally, a relationship between the transition to menopause and impaired sleep has been described, mediated by increased incidence in vasomotor symptoms and obstructive sleep apnea signs during the menopause.

CONCLUSION

Further research is necessary to better characterize and manage nocturia in postmenopausal women.

Hot flashes and awakenings among midlife women

STUDY OBJECTIVES

For most women, the menopause is accompanied by hot flashes and sleep problems. Although hot flashes reportedly wake women from sleep, in the few studies that have used objective measures of both sleep and hot flashes, links between hot flashes and nocturnal awakening have been inconsistent. In a well-characterized cohort of midlife women, we examined the association between objectively assessed hot flashes and actigraphically defined wake from sleep. We hypothesized that wake episodes would be more likely during an objective hot flash relative to minutes without a hot flash.

METHODS

Peri- and postmenopausal midlife women underwent simultaneous objective measurement of hot flashes (sternal skin conductance) and sleep (actigraphy) over 24 hours in the home. The likelihood of waking in the minutes during the hot flash relative to the minutes preceding the hot flash was compared using generalized estimating equations.

RESULTS

We studied 168 women with at least one objective nocturnal hot flash and actigraphy data. Actigraphy-assessed wake episodes were concurrent with 78% of the objective hot flashes. We found an increased likelihood of wake in the minutes during the objective hot flash (0 to +5 min: OR [95% CI] = 5.31 (4.46 to 6.33); p < .0001) relative to the minutes preceding it (-10 to -1 min). The increased likelihood of wake occurred irrespective of whether the women reported the objective hot flash.

CONCLUSION

Among these women who underwent objective measurement of sleep and hot flashes, nocturnal wakefulness was observed with the majority of hot flashes.

Changes in heart rate and blood pressure during nocturnal hot flashes associated with and without awakenings

Hot flashes (HFs) are a hallmark of menopause in midlife women. They are beyond bothersome symptoms, having a profound impact on quality of life and wellbeing, and are a potential marker of cardiovascular (CV) disease risk. Here, we investigated the impact on CV functioning of single nocturnal HFs, considering whether or not they were accompanied by arousals or awakenings. We investigated changes in heart rate (HR, 542 HFs), blood pressure (BP, 261 HFs), and pre-ejection period (PEP, 168 HFs) across individual nocturnal physiological HF events in women in the menopausal transition or post-menopause (age: 50.7 ± 3.6 years) (n = 86 for HR, 45 for BP, 27 for PEP). HFs associated with arousals/awakenings (51.1%), were accompanied by an increase in systolic (SBP; ~6 mmHg) and diastolic (DBP; ~5 mmHg) BP and HR (~20% increase), sustained for several minutes. In contrast, HFs occurring in undisturbed sleep (28.6%) were accompanied by a drop in SBP and a marginal increase in HR, likely components of the heat dissipation response. All HFs were accompanied by decreased PEP, suggesting increased cardiac sympathetic activity, with a prolonged increase for HFs associated with sleep disruption. Older age predicted greater likelihood of HF-related sleep disturbance. HFs were less likely to wake a woman in rapid-eye-movement and slow-wave sleep. Findings show that HFs associated with sleep disruption, which are in the majority and more likely in older women, lead to increases in HR and BP, which could have long-term impact on nocturnal CV restoration in women with multiple HFs.

UTCI as a bio-meteorological tool in the assessment of cold-induced stress as a risk factor for hypertension

BACKGROUND

Hypertension (HT) affects >1/3 of adult populations in developed countries. Several studies reported periodic changes in blood pressure (BP) values depending on atmospheric conditions, and analyzed the impact of outdoor temperature, atmospheric pressure, relative humidity and other meteorological parameters. The Universal Thermal Climate Index (UTCI) is a bio-meteorological index derived from an analysis of human thermal balance that comprehensively describes the impact of meteorological factors, including both cold stress and heat stress and their physiological consequences.

AIM

Our aim was to assess the relationship between UTCI values and the number of consultations for HT within the framework of the healthcare system.

METHODS

This work presents a retrospective epidemiological study of data collected in Olsztyn (Poland), characterized by cold climate type. The analytical material comprised 5578 consultations in emergency departments (EDs) due to HT.

RESULTS

Seasonal differences in the numbers of HT consultations with a significant increase in winter months were noticed, especially as regards women. Under cold stress conditions, the relative risk (RR) related to consultations for HT was 2-fold higher for women as compared to thermoneutral conditions (p < 0.001). For men these differences were also statistically significant, though at a much smaller level (p = 0.03). The increased RR of HT due to cold stress was found among younger and older women contrary to the women at the perimenopausal age.

CONCLUSIONS

Cold stress should be considered as a significant risk factor among patients, particularly women, diagnosed with cardiovascular diseases. The UTCI is an adequate bio-meteorological tool for the assessment of relationships between atmospheric conditions and occurrence of cardiac symptoms.

The Role of Estrogen in Brain and Cognitive Aging

There are 3 common physiological estrogens, of which estradiol (E2) is seen to decline rapidly over the menopausal transition. This decline in E2 has been associated with a number of changes in the brain, including cognitive changes, effects on sleep, and effects on mood. These effects have been demonstrated in both rodent and non-human preclinical models. Furthermore, E2 interactions have been indicated in a number of neuropsychiatric disorders, including Alzheimer's disease, schizophrenia, and depression. In normal brain aging, there are a number of systems that undergo changes and a number of these show interactions with E2, particularly the cholinergic system, the dopaminergic system, and mitochondrial function. E2 treatment has been shown to ameliorate some of the behavioral and morphological changes seen in preclinical models of menopause; however, in clinical populations, the effects of E2 treatment on cognitive changes after menopause are mixed. The future use of sex hormone treatment will likely focus on personalized or precision medicine for the prevention or treatment of cognitive disturbances during aging, with a better understanding of who may benefit from such treatment.

Insomnia and hot flashes

The increased prevalence of sleep disorders associated with menopause has been emphasized by multiple international studies. Many factors are associated with insomnia during menopause, among them: hot flashes (HF), anxiety and depression, other medical conditions, behavioral and psychosocial factors and primitive sleep patterns. The domino hypothesis connects various factors and suggests that HF disturb sleep, thereby causing insomnia, which in turn increases vulnerability to depression. Nevertheless, sleep disorders predict mood disturbances more robustly than vasomotor symptoms (VMS), indicating that sleep also influences mood via other mechanisms. The medical conditions that may compromise sleep in this age group are common; they include obesity, gastroesophageal reflux, cancer, urinary incontinence and nocturia, thyroid dysfunction, chronic pain, fibromyalgia (often starting or worsening in menopause), and hypertension. Common causes of sleep disorders in middle-aged women include poor sleep hygiene, volitional factors, environmental disturbances, alcohol intake, marital dissatisfaction, requests for care from children, grandchildren and/or elderly parents, and financial worries. Evidence from other populations suggests that if insomnia is not treated, it may negatively affect the outcome of comorbid conditions. Taken together, these observations suggest that insomnia should be considered a disorder requiring specific attention and treatment. Moreover, recent cross-sectional data link sleep with subclinical markers of cardiovascular risk. It should also be noted that insomnia is common in patients with mild to moderate obstructive sleep apnea syndrome (OSAS).

Cognitive Behavioral Therapy for Insomnia and Women's Health: Sex as a Biological Variable

Differences in sleep for men and women begin at a very early age, with women reporting poorer sleep and having a higher risk for insomnia compared with men. Women are particularly vulnerable to developing insomnia during times of reproductive hormonal change. Sleep across the woman's lifespan and special treatment considerations for using cognitive behavioral therapy for insomnia (CBT-I) in women will be addressed in this review.

The impact of sleepwear fiber type on sleep quality under warm ambient conditions

BACKGROUND

Sleep disturbance in adults with no health concerns is often linked to the thermal environment. This study assesses the impact on sleep quality of sleepwear made from fibers with different thermal insulation and hygral properties. This randomized cross-over study investigated the effects on sleep quality of sleepwear made from cotton, polyester and Merino wool in adults aged 50-70 years, at an ambient temperature of 30 °C and a relative humidity of 50%.

METHODS

Thirty-six healthy participants completed four nights of sleep study with polysomnography. Participants were categorized by body mass index as <25 kg·m^-2 or ≥25 kg·m^-2, age as <65 years or ≥65 years, and by Pittsburgh Sleep Quality Index (PSQI) as poor sleepers (PSQI≥5) or good sleepers (PSQI<5).

RESULTS

Small, but statistically significant sleep benefits were observed for wool over cotton and polyester sleepwear for multiple sleep parameters, while neither cotton nor polyester was responsible for any statistically significant sleep benefit over the 11 sleep parameters examined. The key findings were: 1) A significant sleepwear effect was observed for sleep onset latency (SOL), p=0.04. 2) For older participants, sleeping in wool significantly reduced SOL (12.4 mins) compared with cotton (26.7 mins, p=0.001) or polyester (21.6 mins, p=0.001). 3) A statistically significant effect was found for sleep fragmentation index (p=0.01) in which wool sleepwear (12.1 no·h^{- 1}) was lower than polyester (13.7 no·h^{- 1}) (p=0.005), but not different to cotton (13.3 no·h^{- 1}). 4) Poor sleepers had less wakefulness when sleeping in wool compared to cotton (p=0.047). 5) And Poor sleepers had higher rapid eye movement sleep latency in polyester than in cotton (p=0.037) or in wool (p=0.036).

CONCLUSION

Statistically significant benefits for wool sleepwear were observed on average for all participants and, in particular, for the older and poorer sleepers. There were no significant differences in any sleep variables between sleepwear types for the BMI sub-group.

Symptoms of menopause - global prevalence, physiology and implications

The symptoms of menopause can be distressing, particularly as they occur at a time when women have important roles in society, within the family and at the workplace. Hormonal changes that begin during the menopausal transition affect many biological systems. Accordingly, the signs and symptoms of menopause include central nervous system-related disorders; metabolic, weight, cardiovascular and musculoskeletal changes; urogenital and skin atrophy; and sexual dysfunction. The physiological basis of these manifestations is emerging as complex and related, but not limited to, oestrogen deprivation. Findings generated mainly from longitudinal population studies have shown that ethnic, geographical and individual factors affect symptom prevalence and severity. Moreover, and of great importance to clinical practice, the latest research has highlighted how certain menopausal symptoms can be associated with the onset of other disorders and might therefore serve as predictors of future health risks in postmenopausal women. The goal of this Review is to describe in a timely manner new research findings on the global prevalence and physiology of menopausal symptoms and their impact on future health.

Sleep problems during the menopausal transition: prevalence, impact, and management challenges

A substantial number of women experience sleep difficulties in the approach to menopause and beyond, with 26% experiencing severe symptoms that impact daytime functioning, qualifying them for a diagnosis of insomnia. Here, we review both self-report and polysomnographic evidence for sleep difficulties in the context of the menopausal transition, considering severity of sleep complaints and links between hot flashes (HFs) and depression with poor sleep. Longitudinal population-based studies show that sleep difficulties are uniquely linked with menopausal stage and changes in follicle-stimulating hormone and estradiol, over and above the effects of age. A major contributor to sleep complaints in the context of the menopausal transition is HFs, and many, although not all, HFs are linked with polysomnographic-defined awakenings, with HF-associated wake time contributing significantly to overall wakefulness after sleep onset. Some sleep complaints may be comorbid with depressive disorders or attributed to sleep-related breathing or movement disorders, which increase in prevalence especially after menopause, and for some women, menopause, age, and environmental/behavioral factors may interact to disrupt sleep. Considering the unique and multifactorial basis for sleep difficulties in women transitioning menopause, we describe clinical assessment approaches and management options, including combination treatments, ranging from cognitive behavioral therapy for insomnia to hormonal and nonhormonal pharmacological options. Emerging studies suggest that the impact of severe insomnia symptoms could extend beyond immediate health care usage and quality of life issues to long-term mental and physical health, if left untreated in midlife women. Appropriate treatment, therefore, has immediate benefit as well as advantages for maintaining optimal health in the postmenopausal years.

Relationship between changes in vasomotor symptoms and changes in menopause-specific quality of life and sleep parameters

OBJECTIVE

This study characterizes and quantifies the relationship of vasomotor symptoms (VMS) of menopause with menopause-specific quality of life (MSQOL) and sleep parameters to help predict treatment outcomes and inform treatment decision-making.

METHODS

Data were derived from a 12-week randomized, double-blind, placebo-controlled phase 3 trial that evaluated effects of two doses of conjugated estrogens/bazedoxifene on VMS in nonhysterectomized postmenopausal women (N = 318, mean age = 53.39) experiencing at least seven moderate to severe hot flushes (HFs) per day or at least 50 per week. Repeated measures models were used to determine relationships between HF frequency and severity and outcomes on the Menopause-Specific Quality of Life questionnaire and the Medical Outcomes Study sleep scale. Sensitivity analyses were performed to check assumptions of linearity between VMS and outcomes.

RESULTS

Frequency and severity of HFs showed approximately linear relationships with MSQOL and sleep parameters. Sensitivity analyses supported assumptions of linearity. The largest changes associated with a reduction of five HFs and a 0.5-point decrease in severity occurred in the Menopause-Specific Quality of Life vasomotor functioning domain (0.78 for number of HFs and 0.98 for severity) and the Medical Outcomes Study sleep disturbance (7.38 and 4.86) and sleep adequacy (-5.60 and -4.66) domains and the two overall sleep problems indices (SPI: 5.17 and 3.63; SPII: 5.82 and 3.83).

CONCLUSIONS

Frequency and severity of HFs have an approximately linear relationship with MSQOL and sleep parameters-that is, improvements in HFs are associated with improvements in MSQOL and sleep. Such relationships may enable clinicians to predict changes in sleep and MSQOL expected from various VMS treatments.

Nocturnal Hot Flashes: Relationship to Objective Awakenings and Sleep Stage Transitions

STUDY OBJECTIVES

While women report sleep interruption secondary to nighttime hot flashes, the sleep disrupting impact of nocturnal hot flashes (HF) is not well characterized. We utilized a model of induced HF to investigate the relationship of nighttime HF to sleep architecture and sleep-stage transitions.

METHODS

Twenty-eight healthy, premenopausal volunteers received the depot gonadotropin-releasing hormone agonist (GnRHa) leuprolide to rapidly induce menopause, manifesting with HF. Sleep disruption was measured on 2 polysomnograms conducted before and after 4-5 weeks on leuprolide, when HF had developed.

RESULTS

165 HF episodes were recorded objectively during 48 sleep studies (mean 3.4 HF/night). After standardizing to sleep-stage time distribution, the majority of HF were recorded during wake (51.0%) and stage N1 (18.8%). Sixty-six percent of HF occurred within 5 minutes of an awakening, with 80% occurring just before or during the awakening. Objective HF were not associated with sleep disruption as measured by increased transitions to wake or N1, but self-reported nocturnal HF correlated with an increase from pre- to post-leuprolide in the rate of transitions to wake (p = 0.01), and to N1 (p = 0.008).

CONCLUSIONS

By isolating the effect of HF on sleep in women without the confound of age-related sleep changes associated with natural menopause, this experimental model shows that HF arise most commonly during N1 and wake, typically preceding or occurring simultaneously with wake episodes. Perception of HF, but not objective HF, is linked to increased sleep-stage transitions, suggesting that sleep disruption increases awareness of and memory for nighttime HF events.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01116401.

Vasomotor and depression symptoms may be associated with different sleep disturbance patterns in postmenopausal women

OBJECTIVE

This study aims to explore the association of vasomotor symptoms (VMS) and depression symptoms with different symptoms of subjective sleep disturbance in postmenopausal women.

METHODS

This is a cross-sectional study of 163 postmenopausal women (not taking hormone therapy) attending a university menopause clinic. Measures included the Athens Insomnia Scale, Greene Climacteric Scale, and Symptom Checklist-90-Revised depression subscale. Covariate-adjusted ordinal logistic regression was used to investigate the association of VMS and depression with each item of the Athens Insomnia Scale.

RESULTS

Controlling for confounding factors, we found VMS to be significantly associated with awakenings during the night (odds ratio [OR], 1.85; P < 0.001), overall quality of sleep (OR, 2.00; P < 0.001), well-being during the day (OR, 1.63; P = 0.008), functioning capacity during the day (OR, 1.72; P = 0.01), and sleepiness during the day (OR, 1.66; P = 0.03); whereas we found Symptom Checklist-90-Revised depression subscale scores to be associated with sleep induction (OR, 2.09; P < 0.001), final awakening earlier than desired (OR, 2.21; P < 0.001), total sleep duration (OR, 1.62; P = 0.01), overall quality of sleep (OR, 1.64; P = 0.009), well-being during the day (OR, 1.67; P = 0.006), functioning capacity during the day (OR, 1.68; P = 0.01), and sleepiness during the day (OR, 1.57; P = 0.04).

CONCLUSIONS

VMS and depression symptoms are associated with different patterns of sleep disturbance. Although both symptoms are related to sleep quality, daytime functioning, and daytime well-being, depression is uniquely associated with difficulty falling asleep and waking up earlier than desired, whereas VMS are related to frequent awakenings during sleep. The findings are limited by the cross-sectional design and relatively small sample size of the study. Recommendations for future research are discussed to guide this line of inquiry and to gain a better understanding of the complex relationship between climacteric and mood symptoms and their contribution to the development of sleep disturbances during menopause.

Magnitude of the impact of hot flashes on sleep in perimenopausal women

OBJECTIVE

To quantify the impact of objectively recorded hot flashes on objective sleep in perimenopausal women.

DESIGN

Cross-sectional study. Participants underwent 1-5 laboratory-based polysomnographic recordings for a total of 63 nights, including sternal skin-conductance measures, from which 222 hot flashes were identified according to established criteria. Data were analyzed with hierarchical mixed-effect models and Spearman's rank correlations.

SETTING

Sleep laboratory.

PATIENT(S)

Thirty-four perimenopausal women (age ± SD: 50.4 ± 2.7 years).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Perceived and polysomnographic sleep measures (sleep quality, amount of time spent awake after sleep onset, and number of awakenings). Subjective (frequency and level of bother) and objective (frequency and amount of hot flash-associated awake time) hot-flash measures.

RESULT(S)

Women had an average of 3.5 (95% confidence interval: 2.8-4.2, range = 1-9) objective hot flashes per night. A total of 69.4% of hot flashes were associated with an awakening. Hot flash-associated time awake per night was, on average, 16.6 minutes (95% confidence interval: 10.8-22.4 minutes), which accounted for 27.2% (SD 27.1) of total awake time per night. Hot flash-associated time awake, but not hot flash frequency, was negatively associated with sleep efficiency and positively associated with waking after sleep onset. In addition, self-reported wakefulness correlated with hot flash-associated waking, suggesting that women's estimates of wakefulness are influenced by the amount of time spent awake in association with hot flashes during the night. Having more perceived and bothersome hot flashes was correlated with more perceived wakefulness and awakenings and more objective hot flash-associated time awake and hot-flash frequency.

CONCLUSION(S)

The presence of physiological hot flashes accounts for a significant proportion of total objective time awake during the night in perimenopausal women.

Efficacy of desvenlafaxine succinate for menopausal hot flashes

INTRODUCTION

The concern for the development of breast cancer, stroke, cardiovascular disease and deep venous thrombosis with the use of hormonal therapy has led to the development of alternative nonhormonal forms of therapy like desvenlafaxine for the management of hot flashes.

AREAS COVERED

This review is based upon a PubMed search and clinical trials. The pharmacokinetics and pharmacodynamics of desvenlafaxine are reviewed. This review outlines the effects of desvenlafaxine in management of severity and frequency of vasomotor symptoms, sleep quality and quality of life in postmenopausal women. The potential adverse effects of desvenlafaxine are summarized.

EXPERT OPINION

Based on the evidence from randomized clinical trials, desvenlafaxine is an alternate viable option for reducing the frequency and severity of hot flashes when other treatments fail. In clinical trials, it has been shown that desvenlafaxine reduced the frequency of hot flashes by 55 - 69%. In the trials so far it appears to have good safety and tolerability profile when the drug is initiated in titrating doses. The optimum dose is 100 mg/day and is to be started at 50 mg/day for 3 days and titrated to 100 mg/day. The most common adverse events reported were nausea, dry mouth, fatigue, constipation, diarrhea and somnolence.

Sleep regulation and sex hormones exposure in men and women across adulthood

This review aims to discuss how endogenous and exogenous testosterone exposures in men and estrogens/progesterone exposures in women interact with sleep regulation. In young men, testosterone secretion peaks during sleep and is linked to sleep architecture. Animal and human studies support the notion that sleep loss suppresses testosterone secretion. Testosterone levels decline slowly throughout the aging process, but relatively few studies investigate its impact on age-related sleep modifications. Results suggest that poorer sleep quality is associated with lower testosterone concentrations and that sleep loss may have a more prominent effect on testosterone levels in older individuals. In women, sex steroid levels are characterized by a marked monthly cycle and reproductive milestones such as pregnancy and menopause. Animal models indicate that estrogens and progesterone influence sleep. Most studies do not show any clear effects of the menstrual cycle on sleep, but sample sizes are too low, and research designs often inhibit definitive conclusions. The effects of hormonal contraceptives on sleep are currently unknown. Pregnancy and the postpartum period are associated with increased sleep disturbances, but their relation to the hormonal milieu still needs to be determined. Finally, studies suggest that menopausal transition and the hormonal changes associated with it are linked to lower subjective sleep quality, but results concerning objective sleep measures are less conclusive. More research is necessary to unravel the effects of vasomotor symptoms on sleep. Hormone therapy seems to induce positive effects on sleep, but key concerns are still unresolved, including the long-term effects and efficacy of different hormonal regimens.

Menopausal hot flashes: mechanisms, endocrinology, treatment

Hot flashes (HFs) are a rapid and exaggerated heat dissipation response, consisting of profuse sweating, peripheral vasodilation, and feelings of intense, internal heat. They are triggered by small elevations in core body temperature (Tc) acting within a greatly reduced thermoneutral zone, i.e., the Tc region between the upper (sweating) and lower (shivering) thresholds. This is due in part, but not entirely, to estrogen depletion at menopause. Elevated central sympathetic activation, mediated through α2-adrenergic receptors, is one factor responsible for narrowing of the thermoneutral zone. Procedures which reduce this activation, such as paced respiration and clonidine administration, ameliorate HFs as will peripheral cooling. HFs are responsible for some, but not all, of the sleep disturbance reported during menopause. Recent work calls into question the role of serotonin in HFs. This article is part of a Special Issue entitled 'Menopause'.

Relationship between objectively recorded hot flashes and sleep disturbances among breast cancer patients: investigating hot flash characteristics other than frequency

OBJECTIVE

The aim of this study was to evaluate the relationship between various characteristics of objectively recorded hot flashes and sleep disturbances in breast cancer patients.

METHODS

Fifty-six women who had completed a similar treatment protocol for a first diagnosis of breast cancer within the previous 3 months wore ambulatory sternal skin conductance and polysomnography devices for a home-based nighttime recording of hot flashes and sleep.

RESULTS

Hot flash frequency was not associated with polysomnographic variables (r = -0.18 to 0.21) or beta-I and beta-II electroencephalographic activities (r = -0.01 and 0.03) but was significantly correlated with increased slow (r = 0.28) and delta (r = 0.32) electroencephalographic activities. A slower hot flash onset and a longer hot flash duration were associated with greater polysomnographic impairments (r = -0.50 to 0.48). Greater sleep disturbances were found during hot flash onset or hot flash plateau as compared with the pre-hot flash period (greater percentage of wake time, lower percentage of stage II sleep, and lower percentage of rapid eye movement sleep, all P values < 0.05). The probability that a stage change to a lighter sleep occurred was significantly greater during hot flash onset (11%) than during hot flash plateau (6%; P = 0.02).

CONCLUSIONS

This study suggests that the speed and duration of hot flashes would contribute more importantly to sleep alterations than hot flash frequency. Sleep disturbances tend to occur simultaneously with hot flashes, suggesting that these two nocturnal symptoms are manifestations of a higher-order mechanism involving the central nervous system.

Menopausal hormone therapy and menopausal symptoms

A majority of women will experience bothersome symptoms related to declining and/or fluctuating levels of estrogen during their menopausal transition. Vasomotor symptoms, vaginal dryness, poor sleep, and depressed mood have all been found to worsen during the menopausal transition. While vasomotor symptoms gradually improve after menopause, the time course can be many years. Vaginal dryness does not improve without treatment, while the long-term course of sleep and mood deterioration is not clearly defined at this time. A small minority of women have vasomotor symptoms that persist throughout the remainder of their lives. These common menopausal symptoms all improve with estrogen treatment. Over the last 10 years, we have witnessed a dramatic reduction in enthusiasm for menopausal hormone therapy, despite its high efficacy relative to other treatments. We have also seen the emergence of sound, evidence-based clinical trials of non-hormonal alternatives that can control the common menopausal symptoms. Understanding the natural history of menopausal symptoms, and the risks and benefits of both hormonal and non-hormonal alternatives, helps the clinician individualize management plans to improve quality of life.

Postmenopausal physiological changes

The hallmark of menopause is the marked reduction of estradiol levels due to ovarian failure. This, among other factors result in hot flashes, the most common menopausal symptom. Hot flashes (HFs) can be measured objectively, both inside and outside the laboratory, using sternal skin conductance, an electrical measure of sweating. We have found that HFs are triggered by small elevations in core body temperature (T C ), acting within a greatly reduced thermoneutral zone. This reduction is caused by elevated central sympathetic activation, among other factors. There is a circadian rhythm of HFs peaking at 1825 h. Imaging studies have shown that hot flash activation begins in the brainstem, followed by the insula and by the prefrontal cortex. HFs in the first, but not the second half of the night can produce awakenings and arousals. This is because rapid eye movement (REM) sleep suppresses thermoregulatory effector responses, which include hot flashes.

Modulation of body temperature and LH secretion by hypothalamic KNDy (kisspeptin, neurokinin B and dynorphin) neurons: a novel hypothesis on the mechanism of hot flushes

Despite affecting millions of individuals, the etiology of hot flushes remains unknown. Here we review the physiology of hot flushes, CNS pathways regulating heat-dissipation effectors, and effects of estrogen on thermoregulation in animal models. Based on the marked changes in hypothalamic kisspeptin, neurokinin B and dynorphin (KNDy) neurons in postmenopausal women, we hypothesize that KNDy neurons play a role in the mechanism of flushes. In the rat, KNDy neurons project to preoptic thermoregulatory areas that express the neurokinin 3 receptor (NK3R), the primary receptor for NKB. Furthermore, activation of NK₃R in the median preoptic nucleus, part of the heat-defense pathway, reduces body temperature. Finally, ablation of KNDy neurons reduces cutaneous vasodilatation and partially blocks the effects of estrogen on thermoregulation. These data suggest that arcuate KNDy neurons relay estrogen signals to preoptic structures regulating heat-dissipation effectors, supporting the hypothesis that KNDy neurons participate in the generation of flushes.

Sleep and sleep disorders in menopausal women

Sleep disorders in the menopause are common. Although these disorders may be due to the menopause itself and/or the associated vasomotor symptoms, the etiology is multifactorial and includes a number of other associated conditions. They may simply arise as part of the aging process and not be specifically related to the decrease in estrogen levels or, alternatively, because of breathing or limb movement syndromes, depression, anxiety, co-morbid medical diseases, medication, pain and/or psychosocial factors. The most commonly encountered sleep disorders in menopausal women include insomnia, nocturnal breathing disturbances and the associated sleep disorders that accompany the restless leg syndrome, periodic leg movement syndrome, depression and anxiety. This review article addresses sleep and the sleep disorders associated with menopause and briefly the role that hormone therapy may play in alleviating these disorders.

Are vasomotor symptoms associated with sleep characteristics among symptomatic midlife women? Comparisons of self-report and objective measures

OBJECTIVE

Many women report vasomotor symptoms (VMS) and sleep problems during the menopausal transition. Although reported VMS are consistently related to reported sleep disturbance, findings using physiologic measures of VMS or sleep have been more mixed. Our objective was to examine whether more VMS during sleep are associated with poorer sleep among midlife women with VMS using physiologic measures of both VMS and sleep.

METHODS

A subcohort of participants (N = 52) with VMS, a uterus and both ovaries, and free of medications affecting VMS from the Pittsburgh site of the Study of Women's Health Across the Nation underwent four 24-hour periods of in-home ambulatory VMS and sleep measurement. Measures included sternal skin conductance for the measurement of VMS, actigraphy for assessing sleep, a VMS diary, and a sleep diary completed before bed and upon waking. Associations between VMS and sleep were evaluated using generalized estimating equations with covariates age, body mass index, medications affecting sleep, race, financial strain, and depressive symptoms.

RESULTS

More VMS recalled upon waking were associated with significantly lower actigraphy-assessed sleep efficiency, significantly higher wakefulness after sleep onset, and somewhat longer sleep latency. Conversely, physiologically measured VMS and VMS reported during the night were largely unrelated to sleep characteristics.

CONCLUSIONS

Associations between VMS and sleep may depend more on the awareness of and recall of VMS rather than solely on their physiologic occurrence.

Perceived control and hot flashes in treatment-seeking breast cancer survivors and menopausal women

BACKGROUND

Lower perceived control over hot flashes has been linked to fewer coping strategies, more catastrophizing, and greater hot flash severity and distress in midlife women, yet this important concept has not yet been studied in breast cancer survivors.

OBJECTIVE

The aim of this study was to explore perceived control over hot flashes and hot flashes in breast cancer survivors compared with midlife women without cancer.

METHODS

Ninety-nine survivors and 138 midlife women completed questionnaires and a prospective, electronic hot flash diary. All data were collected at a baseline assessment before randomization in a behavioral intervention study.

RESULTS

Both groups had moderate perceived control over hot flashes. Control was not significantly related to hot flash frequency but was significantly related to hot flash severity, bother, and interference in both groups. A significantly stronger association between control and hot flash interference was found for survivors than for midlife women. Survivors using hot flash treatments perceived less control than did survivors not using hot flash treatments, whereas the opposite was true in midlife women.

CONCLUSIONS

Findings extend our knowledge of perceived control over hot flashes in both survivors and midlife women.

IMPLICATIONS FOR PRACTICE

Findings emphasize the importance of continued menopausal symptom assessment and management, support the importance of continuing nursing care even for survivors who are already using hot flash treatment, and suggest that nursing interventions aimed at improving perceived control over hot flashes may be more helpful for survivors than for midlife women.

Sleep problems after short-term hormone therapy suspension: secondary analysis of a randomized trial

OBJECTIVE

Because hormone therapy use benefits sleep, sleep problems may occur after suspension. We tested the effects of short-term hormone therapy suspension on sleep problems.

METHODS

A total of 1,704 women aged 45 to 80 years at Group Health were randomized to suspend hormone therapy for 1 or 2 months or to continue using hormone therapy. This study included 1,405 women willing to suspend hormone therapy use who returned both baseline and follow-up questionnaires, administered within approximately 3 months of randomization. We used generalized linear models to examine the relationships between hormone therapy suspension and nine individual items from a modified General Sleep Disturbance Scale (number of days experienced in the past week) and an overall sleep quality index at follow-up. We tested whether age, hormone therapy type, or duration of use modified these relationships.

RESULTS

Suspension of hormone therapy for 1 or 2 months was associated with greater frequency of sleep problems for the overall sleep quality index and most individual sleep items. For example, the incident rate ratios for waking too early (95% CI) were 1.23 (1.10-1.38) for the women in the 1-month suspension group and 1.30 (1.17-1.45) for the 2-month suspension group, compared with women who continued the use of hormone therapy. Age and type of and duration of hormone therapy use did not modify these relationships.

CONCLUSIONS

Short-term hormone therapy suspension was related to moderately greater frequency of sleep problems. Alternative forms of sleep management may benefit women who choose to discontinue hormone therapy use.

Changes in self-reported hot flashes and their association with concurrent changes in insomnia symptoms among women with breast cancer

OBJECTIVE

The aim of this study was to assess longitudinally the relationship between hot flashes and insomnia symptoms in women receiving adjuvant treatments for breast cancer.

METHODS

Fifty-eight participants completed a 7-day daily diary assessing hot flashes, the Menopause-Specific Quality of Life Questionnaire, and the Insomnia Severity Index, before and after chemotherapy or radiotherapy and at a 3-month follow-up evaluation.

RESULTS

A first canonical correlation analysis (n = 55) revealed a marginally significant relationship between pretreatment versus posttreatment change scores in hot flashes and sleep (R = 0.39), and a second analysis (n = 51) showed a significant relationship between posttreatment and follow-up changes in hot flash activity and sleep (R = 0.59).

CONCLUSIONS

These results show that increases in vasomotor symptoms occurring within the few months after the termination of initial adjuvant treatments for breast cancer are significantly associated with concurrent increases in insomnia symptoms and vice versa.