Feeling a chill when settling down for the night is a common experience. This sensation, even in a warm environment, is often a normal part of the body’s preparation for sleep. Understanding why this happens can clarify the experience.
The Body’s Natural Cooling Process
The body’s internal clock, the circadian rhythm, orchestrates physiological changes throughout the day. As evening approaches, this clock signals the body to gradually lower its core temperature. This reduction is a natural step in initiating and maintaining sleep.
This temperature dip is accompanied by a decrease in the body’s metabolic rate. As the body prepares for sleep, its metabolic activity slows down, reducing the amount of heat it generates. This reduced heat production contributes to feeling cooler.
The body also uses vasodilation, expanding blood vessels near the skin’s surface. This allows more blood to flow to extremities like the hands and feet. This increased blood flow helps dissipate heat from the body’s core into the surrounding environment, making the skin feel colder.
Environmental Influences
Your sleeping environment’s temperature significantly influences how cold you feel. A room that is too cool can amplify the body’s natural cooling process. Optimal bedroom temperatures for sleep are generally between 60 and 67 degrees Fahrenheit (15.6 to 19.4 degrees Celsius).
The type and amount of bedding also affect your warmth. Insufficient or thin blankets will not adequately trap the heat your body produces. This can lead to rapid heat loss to cooler surroundings. Similarly, light sleepwear may not provide enough insulation.
Drafts from windows, doors, or air conditioning vents can create localized cold spots. A subtle stream of cool air continuously carries away heat from exposed skin, causing discomfort. Addressing these environmental factors can significantly impact your comfort.
When to Consider Medical Causes
While often a normal physiological response, persistent or intense coldness when lying down can signal an underlying medical condition. Anemia, characterized by reduced red blood cells, can lead to feeling cold due to decreased oxygen delivery. This impacts metabolic processes that generate heat.
Hypothyroidism, an underactive thyroid, can also contribute to cold sensitivity by slowing metabolism and reducing heat production. Poor circulation, caused by conditions like peripheral artery disease or Raynaud’s phenomenon, can also reduce blood flow to extremities, making hands and feet feel perpetually cold.
Certain medications can also impact body temperature regulation. If you consistently experience severe coldness along with other symptoms like fatigue, unexplained weight changes, or numbness, consult a healthcare professional.
Practical Ways to Stay Warm
Adjusting your sleep environment can combat the cold sensation. Maintain your bedroom temperature within the recommended 60 to 67 degrees Fahrenheit range. Use layered bedding to adjust warmth throughout the night, adding or removing blankets as needed. Block drafts by sealing gaps around windows and doors or by repositioning your bed.
Incorporate warm activities into your pre-bedtime routine. A warm bath or shower 90 minutes before bed can temporarily raise your core body temperature. As your body cools, it signals readiness for sleep, and residual warmth can prevent an immediate chill. Wearing warm socks or using a hot water bottle can also provide localized warmth.
Adequate hydration and a balanced diet support overall bodily functions, including temperature regulation. Choose sleepwear made from insulating yet breathable materials, such as flannel or fleece. This can help trap body heat effectively.