Lack Of Sleep: The Surprising Reason For Feeling Warm

There are many reasons why you might feel warm after a poor night's sleep. The ideal temperature for sleep is between 60-67 degrees Fahrenheit (15-19 degrees Celsius), and a higher temperature can make it difficult to fall asleep. A hot environment may cause disrupted or lighter sleep, so it is recommended to keep your bedroom cool (between 54 and 75°F).

Your body temperature follows a natural cycle during a 24-hour period, typically dropping in the evening and rising in the morning. If your body temperature doesn't drop in the evening, it can impair your sleep.

- Your room is too warm, or there is high humidity.

- Your bedding is too thick or made from materials that trap heat, such as fleece or down.

- Your mattress absorbs body heat, such as a memory foam mattress.

- You engaged in pre-sleep activities that increased your body temperature, such as exercise, caffeine consumption, or stressful activities.

- You shared a bed with someone or a pet, increasing the temperature.

- You have an underlying medical condition, such as hyperthyroidism, menopause, or an infection.

- You are experiencing side effects from certain medications, such as antidepressants or hormone-blocking drugs.

High metabolism

People with a high metabolism tend to produce more body heat due to a higher metabolic rate. This can be influenced by various factors, such as body composition, with those who have more lean muscle mass producing more heat.

Sleep and Metabolism

Sleep is intricately connected to metabolic processes in the body and plays a role in maintaining metabolic homeostasis. Sleep loss and sleep disorders have been linked to metabolic and cardiovascular issues. During normal sleep, the metabolic rate decreases by around 15% and reaches its minimum in the morning.

Non-Rapid Eye Movement (NREM) Sleep

NREM sleep is further divided into three stages, with the third and fourth stages considered slow-wave sleep (SWS). During SWS, the body is least metabolically active, and the metabolic rate and brain temperature are lowered to deal with any damage that may have occurred during wakefulness.

Sleep Deprivation and Metabolism

Sleep deprivation can cause metabolic dysregulation through several pathways, including hormonal changes, sympathetic stimulation, and increased inflammation. Studies have shown that sleep deprivation can lead to decreased insulin sensitivity, increased glucose levels, and altered glucose metabolism, which can progress to type 2 diabetes.

Sleep Loss and Appetite

Sleep loss can disrupt the balance of leptin and ghrelin, two hormones that regulate appetite. Leptin inhibits appetite and increases energy expenditure, while ghrelin increases appetite and reduces energy expenditure. Sleep deprivation lowers leptin levels and increases ghrelin levels, leading to increased hunger and a preference for high-carbohydrate foods.

Sleep Loss and Obesity

Chronic sleep deprivation, or sleeping less than eight hours, has been associated with an increase in body mass index (BMI) and obesity. Several studies have found a link between reduced sleep duration and increased body weight, with both short and long sleep durations potentially disrupting metabolic equilibrium.

In summary, high metabolism can contribute to feeling warm, especially when combined with sleep deprivation. Sleep loss can disrupt metabolic processes, increase appetite, and contribute to weight gain, all of which can further elevate body temperature.

Hormone fluctuations

Cortisol follows a circadian rhythm, with levels peaking in the morning and decreasing throughout the day. During sleep, cortisol levels go down even more. However, if you don't get enough sleep, your body temperature might still be trying to drop, which can make you feel chilly.

Hormone changes during menstruation, pregnancy, perimenopause, and menopause can also cause night sweats and hot flashes. For example, fluctuations in estrogen and progesterone levels during the menstrual cycle can lead to night sweats, particularly with premenstrual syndrome. Similarly, hormonal changes during menopause can alter the hypothalamus, which affects body temperature regulation, resulting in hot flashes and night sweats.

In addition, certain medications can affect hormone levels and cause an increase in body temperature. For instance, hormonal contraceptives, thyroid medications, antidepressants, and other psychiatric medications can sometimes lead to higher body temperatures and excessive sweating.

Medication side effects

Feeling warm can be a side effect of certain medications, even when you're not. This can be dangerous in low temperatures, as you are still losing body heat and water vapour.

Antidepressants

Selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants can cause hot flashes and increased sweating, making you feel warmer.

Anxiety Medications

Benzodiazepines, commonly used for anxiety, can make you feel drowsy and weak for a few hours to several days, depending on the medication.

Blood Pressure Medications

Beta-blockers work by slowing down your heart, which can make you feel tired. They also lower your body's level of melatonin, a hormone that helps control your sleep cycle, which can cause you to wake up at night and give you nightmares.

Pain Relievers

Medications such as acetaminophen (Tylenol) or aspirin can affect your body's ability to regulate its temperature.

Hormone Therapy Medications

These can cause night sweats or hot flashes due to hormonal imbalances.

Recreational Drugs

Drugs such as MDMA, ecstasy, and cocaine can affect your body's ability to regulate its temperature.

If you are experiencing side effects from your medication, it is important to consult your doctor or pharmacist. They may suggest adjusting the dosage, changing the medication, or taking it at a different time of day. Do not stop taking any prescription medication without first consulting your doctor.

High room temperature

A high room temperature can cause you to feel warm and uncomfortable at night. The ideal room temperature for sleep is between 60°F and 70°F (15°C and 21°C). A room that is too warm can cause you to stay awake and experience less slow-wave or rapid-eye movement sleep. Humidity can also be a factor, as it reduces the ability of sweat to evaporate, further increasing the feeling of warmth.

To combat a high room temperature, you can try the following:

• Open a window
• Use a dehumidifier
• Use a fan or air conditioning
• Move your mattress to the floor, as heat rises
• Take a cold shower before bed
• Use fewer blankets or choose lightweight and breathable fabrics
• Set your thermostat to a cooler temperature, between 60°F and 67°F (15°C and 19°C)
• Use a fan or air conditioning to increase airflow and circulation
• Avoid caffeine, spicy foods, and alcohol before bed, as these can increase body temperature
• Stay hydrated throughout the day to regulate body temperature and produce sweat

By making these adjustments, you can create a more comfortable sleep environment and improve your overall sleep quality.

Mattress heat absorption

The type of mattress you sleep on can have a significant impact on your sleep quality, especially if you tend to sleep hot. Some mattresses retain a lot of heat, causing you to wake up in the middle of the night feeling sweaty and restless. Memory foam mattresses, for instance, are notorious for heat retention due to the dense nature of the foam and the lack of interconnected air channels. Once the mattress absorbs body heat, it becomes challenging for the heat to escape.

Choosing the Right Mattress

If you're a hot sleeper, it's crucial to select a mattress that doesn't trap heat. Here are some recommendations:

• Gel-infused memory foam or plant-based memory foam: These options have lower heat retention abilities compared to traditional memory foam. Gel-infused memory foam, in particular, has cooling gel that helps the mattress sleep cooler.
• Latex mattresses: Latex mattresses are highly breathable and have an open-cell structure with pinholes that provide ventilation. They are the least likely type of mattress to retain heat, with only 10% of latex mattress users reporting feeling hot at night.
• Innerspring mattresses: Also known as coil mattresses, these have spaces between the coils that allow for air circulation, making them sleep cooler than memory foam.
• Hybrid mattresses: These combine the best of both worlds, usually consisting of latex, memory foam, and/or gel, along with an innerspring system. They are breathable, supportive, and comfortable.

Tips to Keep Your Mattress Cool

In addition to choosing the right type of mattress, here are some tips to help manage mattress heat absorption:

• Create space for airflow: Ensure there is enough space under your mattress to allow for free movement of air. Avoid beds made of solid plywood, as they can trap air and cause the mattress to heat up. Opt for a bed with equally spaced wooden boards instead.
• Invest in cooling mattress toppers: If you're attached to your memory foam mattress, consider using a cooling mattress topper to help dissipate heat.
• Use a mattress protector: Mattress protectors made from breathable materials, such as natural fibers, can help regulate the temperature of your mattress.
• Choose breathable sheets: Opt for cotton, linen, or bamboo sheets, as they are breathable and don't retain heat. Avoid synthetic sheets, as they trap heat.
• Uncover part of your body: This may seem obvious, but uncovering part of your body can help cool you down and improve air circulation.
• Use a cooling pillow: Since we lose around 10% of our body heat through our heads, using a cooling gel pillow can help regulate your overall body temperature.
• Improve your sleep routine: Lower your body temperature before bed by drinking cool water, exercising earlier in the day, and avoiding caffeine close to bedtime.

Frequently asked questions