Waking up feeling cold is a common experience. While your bed provides warmth, various factors can contribute to a chilly awakening. Understanding these influences, from your immediate surroundings to your body’s intricate biological processes, can explain why you might feel cold upon waking. This article explores environmental aspects, physiological changes during sleep, and underlying health conditions that can lead to this sensation.
External Factors and Your Sleep Environment
Your bedroom temperature significantly impacts how you feel upon waking. An excessively cold room can lead to discomfort. Experts suggest an optimal sleeping environment is generally between 60 and 67 degrees Fahrenheit (15.6 and 19.4 degrees Celsius) for most adults. Many homes naturally become cooler in the early morning due to overnight thermostat adjustments or drops in outside air temperature.
The type and amount of bedding you use also play a role in maintaining warmth. Natural fibers are often more breathable, while synthetic fabrics might retain less heat, potentially leading to a chill. Drafts from windows or doors can create cold spots that disrupt thermal comfort. Wearing appropriate sleepwear can help your body maintain a stable temperature, preventing heat loss that could result in feeling cold in the morning.
How Your Body Regulates Temperature During Sleep
Your body’s internal temperature regulation is influenced by your circadian rhythm, the natural 24-hour cycle governing sleep and wakefulness. As bedtime approaches, your core body temperature naturally decreases, signaling your body to prepare for sleep. This downward trend continues throughout the night, typically reaching its lowest point an hour or two before you wake up.
During non-rapid eye movement (NREM) sleep, your brain actively lowers your body and brain temperature, allowing for energy conservation. This cooling facilitates deeper sleep. However, during rapid eye movement (REM) sleep, the brain’s ability to regulate temperature becomes less efficient, and thermoregulatory mechanisms like sweating or shivering are blunted. This means you are more susceptible to external temperature changes during REM sleep, potentially leading to a cold sensation if your environment is cool. The metabolic rate also decreases during sleep, typically by about 15%, further contributing to a lower body temperature.
Underlying Health Considerations
Beyond environmental and physiological factors, various health conditions can contribute to waking up cold. Anemia, where your blood lacks sufficient healthy red blood cells to carry oxygen, can lead to feeling cold, especially in the hands and feet. This occurs because oxygen is essential for calorie burning, heat production, and blood vessel constriction to conserve heat.
Thyroid disorders, particularly hypothyroidism (an underactive thyroid), can disrupt normal body temperature regulation. The thyroid gland produces hormones controlling metabolism; insufficient levels can slow metabolic rate, leading to persistent coldness. This cold intolerance can be felt even in warm environments and is a common symptom of an underactive thyroid. Low blood sugar, also known as hypoglycemia, can also cause a cold feeling, as the body lacks sufficient glucose to generate heat.
Certain medications can induce a feeling of coldness as a side effect. For instance, beta-blockers, prescribed for heart conditions, can reduce blood flow to the extremities, leading to cold hands and feet. Dehydration can also make you feel cold, as your body’s ability to regulate temperature is impacted by fluid levels, potentially leading to chills. Chronic lack of sleep can increase sensitivity to cold by disrupting normal blood flow regulation in the skin.
When to Seek Professional Advice
While waking up cold can often be attributed to easily adjustable environmental factors or normal physiological processes, persistent or concerning symptoms warrant medical attention. If you consistently wake up feeling cold despite optimizing your sleep environment and have accompanying symptoms, consult a healthcare professional. These might include unexplained fatigue, significant weight changes, or unusual tingling or numbness in your extremities.
Seeking professional advice is important if the cold sensation significantly impacts your daily life or if you suspect an underlying health condition. Conditions like undiagnosed thyroid disorders, anemia, or diabetes can become more serious if left untreated. A doctor can evaluate your symptoms, perform necessary tests, and determine if a medical condition contributes to your cold sensations, guiding you toward appropriate management or treatment.