According to Dr. Kelvas, when the room is too hot or cold, the body has difficulty regulating these hormones, which can lead to difficulty falling asleep or staying asleep.

The common recommendation for ambient room temperature is in the range of 60 °F (15.5 °C) to 68 °F (20 °C), as per the Sleep Foundation. It’s been found to aid the body’s thermoregulatory process to promote healthy sleep latency (the time it takes to fall asleep) and good quality sleep overall.

Temperature and the body

Regardless of the outside temperature, the thermoregulatory system of the human body allows us to maintain a healthy internal body temperature. Sweating, shivering, and variations in blood flow to the skin are just a few of the intricate physiological reactions the body uses to control body temperature.

One of the body’s main cooling processes is sweating. Sweat glands generate moisture that evaporates from the skin’s surface when the body’s internal temperature rises, releasing heat and causing the body to cool.

Conversely, shivering is the body’s mechanism for generating heat when the internal temperature drops. Shivering is a reflexive response that causes muscles to contract rapidly, generating heat to raise the body’s temperature.

Vasodilation, dilation, and constriction of blood vessels can also have effects on body temperature. For example, blood vessels near the skin’s surface dilate when the body needs to cool down, allowing more blood to flow through them. This increase in blood flow helps to release heat from the body. On the other hand, when the body needs to conserve heat, blood vessels near the skin’s surface constrict, reducing blood flow and conserving heat.

As you prepare for bed and transition into the various stages of sleep, each of these processes is crucial. This change in temperature might be familiar to you. Wearing socks, for instance, can make you feel a little warmer when you are feeling cold in bed because our hands and feet lose a lot of heat. You will therefore feel warmer if you cover them. On the other hand, extending your feet out from beneath the blanket could provide the necessary heat relief to help you fall asleep if you feel warm under the covers but do not want to completely remove the blanket.

Temperature and sleep

Temperature has been a powerful indicator of sleep and wakefulness throughout human existence. It acts as an external cue that affects our circadian cycle, often known as a “zeitgeber” or time-giver. Researchers examined sleep in three geographically different pre-industrial communities and discovered that people fell asleep as soon as the outside temperature started to drop and continued to do so as the temperature dropped. The temperature of the fingers also showed vasoconstriction, or the narrowing of blood vessels, which was associated with waking up frequently before daybreak when the outside temperature was at its lowest.

Additionally, thermoregulation and temperature impact the different stages of sleep. It’s been found that about two hours before sleep onset, your core body temperature begins to drop and reaches its lowest point during slow-wave sleep. Additionally, the temperature in the brain also slightly decreases at this time.

Our core body temperature hovers around 98.6 °F (37 °C) but fluctuates by about two degrees Fahrenheit during the night.

Decrease in one’s core body temperature during sleep stems from reducing our metabolic output, decreased muscle tone, and decreased sympathetic tone from vasodilation leading to heat loss distally.Valerie Cacho, MD, Integrative Sleep Physician, and Women’s sleep expert

According to Dr. Cacho, while melatonin is most often associated with light exposure, a cool room and the drop in body temperature can also help to increase the production of this “sleep hormone.”

Studies have shown that an excessively warm environment can negatively affect both the slow-wave sleep (SWS) and rapid eye movement (REM) phases of sleep. Your brain is most active during the REM sleep period, which is when dreams happen. Conversely, SWS is linked to a decrease in brain activity but an increase in physiological recoveries, including the release of human growth hormone, muscular repair, and the removal of toxic substances from the brain, including beta-amyloid plaques. But for the best possible bodily and mental health, both are crucial.

Looking at 10 elderly men’s responses to higher bedroom temperatures and their sleep quality, researchers found that even mild heat exposure during the nighttime sleep period would increase the thermal load, decrease REM, and increase wakefulness and whole-body sweat loss.

In addition, research at the University of California, Los Angeles found that warm-blooded animals with higher body temperatures have lower amounts of REM sleep, while those with lower body temperatures have more REM sleep.

The quality of sleep is also influenced by humidity. According to one study, exposure to humid heat lowered SWS and REM sleep while increasing alertness. The drop in core body temperature was also inhibited by humidity.

On the contrary, when your room is too cold, Dr. Kelvas claimed that the body may need to expend energy to stay warm, which can keep it from entering a deeper sleep.

Benefits of sleeping in a cold room

Although it may seem insignificant, many people who have experienced a summer heat wave can attest to the significant impact that room temperature has on sleep. For instance, if you did not have air conditioning, have you ever had to sleep with a cool towel on top of you or downstairs in the living room where there was more air? Or have you ever experienced nocturnal sweats and woken up feeling sleepy? Hormonal changes during menopause increase a woman’s sensitivity to outside temperatures. Furthermore, a cycling woman’s body temperature varies slightly throughout the course of the month. More specifically, during ovulation, it has been seen to rise.

An optimal bedroom temperature, however, goes further than simply helping you wake up more refreshed. Here are four benefits of a cool room that will make you want to dial down your thermostat tonight.

Better sleep quality

Sleeping in a cold room allows your body to release adequate amounts of melatonin and prevents cortisol (stress hormone) from rising and waking you up. Studies have shown that when you create the environment for the body to drop its core temperature throughout the night, you’ll spend more time in two of the most important restorative sleep phases: REM and slow-wave deep sleep. Additionally, you won’t have to worry about night sweats waking you up and causing sleep disturbances at night.

Fall asleep faster

To go to sleep, your body’s core temperature has to decrease. By creating an atmosphere that allows your body to release excess heat and supports its natural circadian rhythm, you will be able to fall asleep more quickly. If your sleep latency is between 10 and 20 minutes, it is generally regarded as healthy. For instance, those who suffer from insomnia often have trouble falling asleep because their bodies have a greater core temperature, which keeps them awake as their bodies attempt to cool down. Their sleep may be disrupted or delayed as a result.

Better weight management

Cold temperatures activate the body’s “brown fat,” which is a very metabolically active tissue, also known as good fat. The more brown fat you have, the more white fat (the fat around your tummy) will burn. Researchers in Australia put men through a controlled sleep environment with different room temperatures. They found that following a month of sleeping in a cooler environment at 66 °F (18.8 °C), the volume of beneficial brown fat in the body had nearly doubled.

Lower risk of diseases

Because of the increase of brown fat, insulin sensitivity increases, which can be key to preventing type 2 diabetes and other metabolic conditions. The Australian study also found that during the time participants slept in the 66 °F (18.8 °C) room, they burned more calories during the day.

Additionally, by allowing the body to access all of the restorative stages of sleep and obtaining the requisite seven to nine hours of sleep, sleeping in a cold environment may help prevent Alzheimer’s disease. Both short and long sleep durations were linked to worse outcomes for older adults, including “greater beta-amyloid plaque burden, greater depressive symptoms, higher body mass index, and cognitive decline, underscoring the importance of maintaining adequate sleep,” according to a cross-sectional study published in the journal JAMA Neurology.