Optimise Temperature

This systematic review explored how rising ambient temperatures affect sleep quality and quantity. The review found consistent evidence that higher nighttime temperatures negatively impact sleep duration and quality, with greater effects in warmer regions, during summer, and among vulnerable groups like older adults. Poor sleep, linked to impaired cognitive function and health, highlights the need for strategies to mitigate heat exposure as global temperatures rise, such as cooling technologies or better urban design.

The sleep Foundation article discusses the optimal bedroom temperature for sleep, recommending approximately 65°F (18.3°C), with a suggested range between 60-67°F (15.6-19.4°C). Maintaining this cooler environment aligns with the body's natural thermoregulation during sleep, facilitating the drop in core body temperature that promotes sleep onset and quality. Proper sleep is crucial for brain health, aiding in memory consolidation, emotional regulation, and overall cognitive performance. To enhance sleep quality and, consequently, cognitive function, consider adjusting your bedroom thermostat to the recommended range, using breathable bedding materials, and keeping the sleep environment dark and quiet. The article is based on current scientific understanding and provides practical guidance for individuals seeking to improve their sleep and brain health.

This study investigated how changes in core body temperature (CBT) before sleep relate to nocturnal heart rate variability (HRV), an indicator of cardiac health, in poor sleepers. It found that individuals with a slower decline in CBT before sleep had higher heart rates and lower HRV during the night, reflecting reduced parasympathetic activity. This suggests that inefficient presleep thermoregulation may impair sleep quality and cardiovascular recovery, emphasizing the link between temperature regulation and brain and heart health.

This study explored the combined effects of daytime melatonin administration and bright light exposure on alertness and body temperature. Melatonin increased sleepiness and altered thermoregulation, raising distal skin temperature. Bright light exposure, however, failed to counter melatonin-induced sleepiness or improve performance but did impact body temperature by increasing proximal and core temperature. These findings suggest melatonin regulates alertness and thermoregulation independently of light's effects, emphasizing the complexity of their interaction.

This study examined how varying air temperatures based on sleep stages impacted sleep quality using an IoT-based temperature control system. Ten participants slept in two settings: one with a constant temperature and another adjusting temperatures according to sleep stages. Results showed that dynamic temperature control improved subjective sleep quality, particularly for deep sleep and reduced awakenings. This approach underscores the potential for using tailored thermal environments to enhance sleep quality, promoting better cognitive function and health.

This review highlights the impact of thermal environments on sleep and circadian rhythms. High temperatures disrupt deep and REM sleep, while low temperatures alter cardiac autonomic activity without affecting sleep stages. Humid conditions worsen heat-related sleep disturbances. Maintaining an optimal thermal environment supports sleep quality, crucial for cognitive function and overall health. Additionally, thermoregulation is closely tied to circadian rhythms, influencing core body temperature and sleep onset.

The Healthline article discusses research indicating that taking a warm bath 1 to 2 hours before bedtime, with water temperatures between 104°F and 109°F (40°C to 43°C), can enhance sleep quality. This practice may help individuals fall asleep approximately 10 minutes faster than usual. The warm bath facilitates the body's thermoregulation process, promoting a natural decline in core temperature that signals readiness for sleep. Improved sleep quality is crucial for brain health, as it supports cognitive functions like memory consolidation and emotional regulation. Incorporating a warm bath into an evening routine can serve as an effective, non-pharmacological strategy to enhance sleep hygiene and, consequently, cognitive performance. The recommendations are based on a systematic review of multiple studies, providing a robust foundation for these conclusions.

This study linked nighttime temperature anomalies with insufficient sleep using data from 765,000 U.S. residents between 2002–2011. A 1°C increase in nighttime temperature resulted in approximately three additional nights of insufficient sleep per 100 individuals monthly. Effects were most pronounced in summer, among elderly and low-income populations, highlighting vulnerability to heat. Projections suggest climate change may significantly increase sleep loss by 2050 and 2099, affecting cognitive function and health on a large scale.

This study used data from 47,628 adults across 68 countries to explore the impact of rising nighttime temperatures on sleep. Higher temperatures were linked to reduced sleep duration and increased risk of insufficient sleep, particularly in summer, among older adults, women, and people in low-income regions. Hotter climates showed greater sleep loss per degree of warming, with no evidence of short-term adaptation. By 2099, under high-emissions scenarios, nighttime heat could lead to significant global sleep loss, exacerbating health and productivity issues tied to insufficient rest.

This study examined seasonal variations in sleep architecture using data from 188 patients with neuropsychiatric sleep disturbances. Findings showed longer total sleep times and more REM sleep in winter compared to summer, with slower wave sleep (deep sleep) stable except for a decline in autumn. REM latency (time to enter REM sleep) was shorter in autumn and winter. These patterns suggest that human sleep is influenced by seasonal changes, even in urban environments with artificial lighting, which may impact cognitive function and overall well-being.

This review explored the interplay between sleep and thermoregulation, focusing on how body temperature affects sleep stages. Cooling before sleep supports falling into deep (NREM) sleep by lowering core body temperature, while REM sleep often raises brain temperature slightly. Techniques like warm baths can improve sleep onset by promoting heat loss from extremities. Thermoregulation is vital for energy conservation and cellular recovery during sleep, linking temperature regulation to cognitive function and overall health.

The sleep Foundation article "The Best Temperature for sleep" discusses how bedroom temperature affects sleep quality. It recommends maintaining a bedroom temperature around 65°F (18.3°C), with a suggested range between 60-67°F (15.6-19.4°C), to support the body's natural thermoregulation during sleep. A cooler environment facilitates the body's core temperature drop, promoting better sleep onset and maintenance. The article also notes that individual preferences may vary, and adjustments should be made accordingly.Maintaining an optimal sleep environment is crucial for brain health and cognitive performance, as quality sleep enhances memory consolidation and cognitive functions. To improve sleep quality, it's advisable to keep the bedroom cool, use breathable bedding, and establish a consistent sleep routine. Given the sleep Foundation's expertise and the evidence provided, these recommendations are credible and practical for enhancing sleep and cognitive health.

This study examined how different types of sleepwear and bedding (cotton vs. wool and polyester vs. wool) affected sleep quality under ambient temperatures of 17°C and 22°C. Wool sleepwear significantly reduced sleep onset latency (time to fall asleep) compared to cotton at cooler temperatures (17°C), promoting better sleep efficiency. However, at warmer temperatures (22°C), cotton led to slightly better deep sleep. Bedding type had no significant impact. These findings suggest that thermal properties of sleepwear play a role in sleep quality by influencing body temperature regulation.

This study evaluated how high temperatures (28°C, 32°C, 36°C, and 38°C) influence sleep quality and appetite. sleep at 32°C resulted in the best quality, with the longest total sleep duration and minimal disturbances, while 36°C and 38°C led to significant declines in sleep quality, including reduced total sleep time and increased shallow sleep. High temperatures also suppressed appetite, particularly at lunch, with lower food intake and shorter meal durations. These findings highlight the impact of thermal environments on rest and nutritional behavior, vital for maintaining cognitive and physical health.

This review explores the intricate relationship between body temperature regulation and sleep, focusing on how temperature changes influence sleep onset and quality. During sleep, core body temperature drops while extremities warm, promoting non-rapid eye movement (NREM) sleep. This process, driven by the brain's thermoregulatory circuits, helps maintain energy balance and supports cognitive recovery. Disruptions in temperature regulation can lead to sleep difficulties, highlighting the importance of a stable thermal environment for optimal rest.