Warm Feet and Sleep

Researchers writing in the medical journal Physiology and Behavior say they “present new data indicating age- and insomnia-related changes in the sleep-onset latency response to foot warming, and evaluate whether different methods of foot warming could provide an applicable strategy to address sleep complaints.”

Physiol Behav. 2007 Feb 28;90(2-3):257-66. Raymann RJ, Swaab DF, Van Someren EJ.

Skin temperature and sleep-onset latency: Changes with age and insomnia.

Throughout the 24-hour day, the occurrence of sleep and wakefulness is closely related to changes in body temperatures.

Changes in skin temperature may causally affect the ability to initiate and maintain sleep.

First, we briefly summarize a previously proposed neurobiological mechanism that couples skin temperature to sleep propensity. Next we review previous findings on the relation between skin temperature and sleep-onset latency, indicating that sleep propensity can be enhanced by warming the skin to the level that normally occurs prior to – and during – sleep. Finally, we present new data indicating age- and insomnia-related changes in the sleep-onset latency response to foot warming, and evaluate whether different methods of foot warming could provide an applicable strategy to address sleep complaints. Foot temperature manipulations included footbaths before sleep onset (1), and heatable bed socks applied either before (2) or after lights-off (3).

In adults, sleep-onset was accelerated by warm and neutral bed socks after lights-off and correlated to the increase in foot temperature. This increase was attenuated in elderly subjects. In elderly subjects without sleep difficulties, sleep onset could be accelerated with neutral bed socks after lights-off and a warm footbath prior to lights-off. In elderly insomniacs, none of the treatments accelerated sleep onset. We illustrate that elderly subjects show an attenuated increase in foot temperature after lights-off and lose the relationship between pre-sleep heat-loss activation and sleep latency. The sensitivity of sleep propensity to foot warming changes with age and is attenuated in age-related insomnia.

Sleep

Sleep and Diabetes Risk in Men Is Testosterone Also Involved?
Researchers writing in the medical journal Diabetes Care say that too little or too much sleep increases diabetes risk. The researchers say that men getting 5 to 6 hours of sleep a night were twice as likely to develop diabetes, men getting more than 8 hours were three times more likely to develop diabetes. They also noted that testosterone may be a factor in sleep on diabetes.

Poor Sleep and Cognitive Function
Researchers writing in the medical journal The Journals of Gerontology Series A: Biological Sciences and Medical Sciences say that Disturbed Sleep was related to poorer cognition.

Hot Flashes and Insomnia
Researchers writing in the Archives of Internal Medicine say: “Severe hot flashes are strongly associated with chronic insomnia in midlife women. The presence of hot flashes should be systematically investigated in women with insomnia. Treating hot flashes could improve sleep quality and minimize the deleterious consequences of chronic insomnia.”

Hot Flashes and Sleep
Researchers writing in the medical journal Menopause say that ambient temperature and REM sleep patterns effect sleep in postmenopausal women.

Warm Feet and Sleep
Researchers writing in the medical journal Physiology and Behavior say they “present new data indicating age- and insomnia-related changes in the sleep-onset latency response to foot warming, and evaluate whether different methods of foot warming could provide an applicable strategy to address sleep complaints.”

Melatonin Research

Blood Pressure
Scheer FA, Van Montfrans GA, van Someren EJ, et al. Daily nighttime melatonin reduces blood pressure in male patients with essential hypertension. Hypertension 2004;43:192-7.

Study: Researchers sought to examine whether hypertension could be lowered by better sleep.

The researchers stated: “In patients with essential hypertension, repeated bedtime melatonin intake significantly reduced nocturnal blood pressure. Future studies in larger patient group should be performed to define the characteristics of the patients who would benefit most from melatonin intake. The present study suggests that support of circadian pacemaker function may provide a new strategy in the treatment of essential hypertension.”

Melatonin’s Beneficial Effects on Night-Time Blood Pressure and Women Aged 47 to 63
Researchers writing in the American Journal of Hypertension examined the question: “The nocturnal decline of blood pressure (BP) is almost coincident with the elevation of melatonin, which may exert vasodilatating and hypotensive effects. In this study we investigated whether prolonged nocturnal administration of melatonin could influence the daily rhythm of BP in women.”

How was the study conducted?
“In a randomized double-blind study, 18 women, 47 to 63 years of age (nine with normal blood pressure and nine being treated treated for essential hypertension) received a 3-week course of a slow-release melatonin pill (3 mg) or placebo 1 hour before going to bed. They were then crossed over to the other treatment for another 3 weeks.”

What did they conclude?
“In comparison with placebo, melatonin administration did not influence (daytime) BP but did significantly decrease nocturnal systolic, diastolic, and mean BP without modifying heart rate. The effect was inversely related to the day–night difference in BP…These data indicate that prolonged administration of melatonin may improve the day–night rhythm of BP, particularly in women with a blunted nocturnal decline.”

Cagnaccia A, Cannolettaa M, Renzia A, Baldassaria F, Aranginob S, Volpea A. Prolonged Melatonin Administration Decreases Nocturnal Blood Pressure in Women. American Journal of Hypertension. Volume 18, Issue 12, Pages 1614-1618

Immune Stimulation
Poon AM, Liu ZM, Pang CS, et al. Evidence for a direct action of melatonin on the immune system. Biol Signals. 1994 Mar-Apr;3(2):107-17.

From the abstract: “Pineal melatonin modulates the mammalian immune system. In vivo studies showed that melatonin enhanced the natural and acquired immunity while in vitro studies demonstrated its inhibitory influence.”

Melatonin, Immune Function and Aging
Researchers writing in the medical Journal Immunity & Aging say: (From the abstract) “Aging is associated with a decline in immune function (immunosenescence), a situation (sp) known to correlate with increased incidence of cancer, infections and degenerative diseases….Melatonin has the potential therapeutic value to enhance immune function in aged individuals and in patients in an immunocompromised state.”

Venkatramanujam Srinivasan, Georges J.M. Maestroni, Daniel P. Cardinali, Ana I. Esquifino, S. R. Pandi-Perumal and Sandra C. Miller. Melatonin, Immune Function and Aging. Immunity & Ageing 2005, 2:17

Read the abstract

Melatonin Randomized Trial for Insomnia in the Elderly
Nalaka S. Gooneratne, MD,MSc, Principal Investigator, University of Pennsylvania
Study start: October 2004; Expected completion: July 2007

From the study details “Melatonin is a hormone secreted predominantly during the sleep period, suspected to have a strong link to the circadian sleep-wake cycle. Melatonin is also available in a pill form and, when administered during the day, tends to have a sedative effect. Clinical trials that have examined the nocturnal effects of melatonin have focused on patients of any age who have insomnia, regardless of their endogenous melatonin levels. Data indicate, however, that individuals with low endogenous melatonin levels may be more responsive to exogenous melatonin. Generally, melatonin levels decrease with age; therefore, older individuals with insomnia represent an ideal population in which to study the effects of exogenous melatonin on sleep. This study will provide older adults with insomnia melatonin tablets to determine whether the tablets will increase their sleep.”

Read more about this current research

Melatonin and Alzheimer-like Neurodegeneration
Writing in the medical journal Acta Pharmacologica Sinica, researchers studied the effect of melatonin and cognitive impairment. They wrote: “Alzheimer disease (AD), an age-related neurodegenerative disorder with progressive loss of memory and deterioration of comprehensive cognition, is characterized by extracellular senile plaques of aggregated beta-amyloid (Abeta), and intracellular neurofibrillary tangles that contain hyperphosphorylated tau protein. Recent studies showed that melatonin, an indoleamine secreted by the pineal gland, may play an important role in aging and AD as an antioxidant and neuroprotector. Melatonin decreases during aging and patients with AD have a more profound reduction in this hormone. Data from clinical trials indicate that melatonin supplementation improves sleep, ameliorates sundowning, and slows down the progression of cognitive impairment in Alzheimer patients.” Wang JZ, Wang ZF. Acta Pharmacol Sin. 2006 Jan;27(1):41-9.

Read the abstract here

Does Melatonin Protect Vision As We Age?
Researchers writing in the Journal of Pineal Research say that Melatonin maybe beneficial in preserving visual functions.

Excerpts from the study abstract:
“Current evidence suggests that melatonin may act as a protective agent in ocular conditions such as photo-keratitis, cataract, glaucoma, retinopathy of prematurity and ischemia/reperfusion injury.

These diseases are sight-threatening and they currently remain, for the most part, untreatable. The pathogenesis of these conditions is not entirely clear but oxidative stress has been proposed as one of the causative factors.

Oxidative damage in the eye leads to apoptotic degeneration of retinal neurons and fluid accumulation. Retinal degeneration decreases visual sensitivity and even a small change in the fluid content of the cornea and crystalline lens is sufficient to disrupt ocular transparency. In the eye, melatonin is produced in the retina and in the ciliary body. Continuous regeneration of melatonin in the eye offers a frontier antioxidative defense for both the anterior and posterior eye.

However, melatonin production is minimal in newborns and its production gradually wanes in aging individuals as indicated by the large drop in circulating blood concentrations of (Melatonin).

These individuals are possibly at risk of contracting degenerative eye diseases that are free radical-based. Supplementation with melatonin, a potent antioxidant, in especially the aged population should be considered as a prophylaxis to preserve visual functions.”

Siu AW, Maldonado M, Sanchez-Hidalgo M, Tan DX, Reiter RJ. Protective effects of melatonin in experimental free radical-related ocular diseases. J Pineal Res. 2006 Mar;40(2):101-9.

Hot Flashes and Sleep

Researchers writing in the medical journal Menopause say that ambient temperature and REM sleep patterns effect sleep in postmenopausal women.

Freedman RR, Roehrs TA.Effects of REM sleep and ambient temperature on hot flash-induced sleep disturbance. Menopause. 2006 Jul-Aug;13(4):576-83.

From the study abstract:
OBJECTIVE:: To determine whether hot flashes produce sleep disturbance in postmenopausal women.

DESIGN:: This study was performed in a university medical center laboratory with 18 postmenopausal women with hot flashes, six with no hot flashes, and 12 cycling women, all healthy and medication free. Polysomnography, skin and rectal temperatures, and skin conductance to detect hot flashes were recorded for four nights.

Nights 2, 3, and 4 were run at 30 degrees C (86 degrees F), 23 degrees C (about 73.5 degrees F), and 18 degrees C (about 64.5 degrees F) in randomized order.

RESULTS:: During the first half of the night, the women with hot flashes had significantly more arousals and awakenings than the other two groups and the 18 degrees C ambient temperature (about 64.5 degrees F) significantly reduced the number of hot flashes.

These effects did not occur in the second half of the night. In the first half of the night, most hot flashes preceded arousals and awakenings. In the second half, this pattern was reversed.

CONCLUSIONS: In the second half of the night, rapid eye movement sleep suppresses hot flashes and associated arousals and awakenings. This may explain previous discrepancies between self-reported and laboratory-reported data in postmenopausal women with hot flashes.

Hot Flashes and Insomnia

Researchers writing in the Archives of Internal Medicine say: “Severe hot flashes are strongly associated with chronic insomnia in midlife women. The presence of hot flashes should be systematically investigated in women with insomnia. Treating hot flashes could improve sleep quality and minimize the deleterious consequences of chronic insomnia.”

Ohayon MM. Severe hot flashes are associated with chronic insomnia. Arch Intern Med. 2006 Jun 26;166(12):1262-8

BACKGROUND: Because hot flashes can occur during the night, their presence has been frequently associated with insomnia in women with symptoms of menopause. However, many factors other than hot flashes or menopause can be responsible for insomnia, and several factors associated with insomnia in the general population are also commonly observed in perimenopausal and postmenopausal women who have hot flashes.

METHODS: A random sample of 3243 subjects (aged >/=18 years) representative of the California population was interviewed by telephone. Included were 982 women aged 35 to 65 years. Women were divided into 3 groups according to menopausal status: premenopause (57.2%), perimenopause (22.3%), and postmenopause (20.5%). Hot flashes were counted if they were present for at least 3 days per week during the last month and were classified as mild, moderate, or severe according to their effect on daily functioning.

Chronic insomnia was defined as global sleep dissatisfaction, difficulty initiating sleep, difficulty maintaining sleep, or nonrestorative sleep, for at least 6 months. Diagnoses of insomnia were assessed according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, classification.

RESULTS: Prevalence of hot flashes was 12.5% in premenopause, 79.0% in perimenopause, and 39.3% in postmenopause. Prevalence of chronic insomnia was reported as 36.5% in premenopause, 56.6% in perimenopause, and 50.7% in postmenopause.

Prevalence of symptoms of chronic insomnia increased with the severity of hot flashes, reaching more than 80% in perimenopausal women and postmenopausal women who had severe hot flashes. In multivariate analyses, severe hot flashes were significantly associated with symptoms and a diagnosis of chronic insomnia. Poor health, chronic pain, and sleep apnea were other significant factors associated with chronic insomnia.

CONCLUSIONS: Severe hot flashes are strongly associated with chronic insomnia in midlife women. The presence of hot flashes should be systematically investigated in women with insomnia. Treating hot flashes could improve sleep quality and minimize the deleterious consequences of chronic insomnia.