Why Do I Get Cold at Night?

6 min read

Last Modified 22 July 2022 First Added 2 January 2020

By Jessica Kadel

At some point, we’ve all woken up shivering and clutching the duvet in the middle of the night due to the cold. This common phenomenon affects most people and is mainly due to internal factors rather than your surroundings. We consider the science behind why you might be reaching for those extra blankets come 3 am and what you can do to combat feeling cold at night.

Why do I get cold when I sleep?

Getting cold at night is completely natural, as to prepare you for sleep, your body’s core temperature drops. this is likely to be linked to your circadian rhythms, which helps you know when it’s time to sleep and time to wake up.

Your core temperature is usually 36°C to 39°C, however, it drops a degree or two overnight. This is a natural response due to a lack of exposure to light and lets your body know it’s time to rest. According to WebMD, a drop in temperature allows you to have a good night’s sleep, which is often why exercising less than an hour before bed isn’t recommended, as it heats the body.

Come daytime, natural or artificial light sends signals to your brain’s hypothalamus which then alerts the body’s natural clock, the suprachiasmatic nucleus. This lets you know it’s time to wake up but also raises your body temperature back up for the day. 

Why being cold helps you sleep

Why we have evolved to become cold at night is still a mystery, though it seems to be linked to various cycles in the body.

Some evidence suggests that the temperature drop in your body at night helps to control other cycles, not just sleeping and waking. This drop may affect the organs and what they do.

Another theory is that the drop in temperature is linked to a drop in metabolism, which is actually a signal for sleep.  A drop in metabolic rate means a drop in heat production. Metabolism can drop as much as 10% in humans during sleep!

Actually sleeping at night could also be the reason for the temperature drop. As night is colder than a day, keeping your body temperature higher would cost more energy. Having a time (like sleep) where you use as little energy as possible would be advantageous for our ancestors who probably struggled to find enough food.

What else causes a person to be cold at night?

Although this drop of body temperature is often a helpful nudge towards the land of nod, there can sometimes be other causes of feeling cold at night, mainly certain medical conditions. If you often find yourself shivering while your partner is having a good night’s rest, it could be due to the following health problems:

1. Anaemia

Anaemia is a very common condition and occurs when your body struggles to make sufficient red blood cells to carry oxygen throughout the body. This will result in regular fatigue, irregular heartbeats and often feeling cold.

Read more about anaemia here.

2. Hypothyroidism (Underactive thyroid)

This occurs when your thyroid (a gland at the base of your neck) struggles to generate or process the thyroid hormone. Feeling cold is a regular symptom of hypothyroidism. However, weight gain, thinning hair, and constipation are other things to look out for.

See more symptoms for hypothyroidism here.

3. Anorexia

The eating disorder anorexia can cause you to be cold at night. Because of not eating and drastic weight loss, anorexics do not have the fat resources to keep them warm. This condition is also a serious mental health issue, and it’s important to get help for this disorder.

Find out more about anorexia and how to get support here.

4. A blood vessel disorder

If your main problem is cold hands and feet at night, then this could be due to blood flow. The cause of cold feet at night is sometimes due to clotting disorders, the blood vessels narrowing, or spasms of the arteries. If you feel this might be the cause, look out for tingling and throbbing in your arms and legs, or white or blue pigment of your fingers and toes.

Find out more here.

5. Diabetes

Finally, another potential cause for feeling cold at night could be diabetes. Although unlikely, the kidney damage from diabetes results in feeling cold all the time, nausea, shortness of breath and swelling of the hands and feet.

See more symptoms and the causes of diabetes here.

What could cause you to wake up shivering?

If you’re not just waking up cold, but actually shivering, this could be a sign of further health conditions. This  can include:

Menopause

Hormonal changes linked to menopause can cause a (previously) menstruating person to get chills at night. These can happen on their own, or after a hot flush.

Find out more about menopause here.

Infection

An immune reaction to an infection is often associated with fever, but this can also cause chills. This is caused by muscles quickly contracting and relaxing. These chills often predict a fever coming.

What kind of vitamin deficiency makes you cold?

Various vitamin deficiencies can cause you to feel so cold at night that it’s difficult to sleep. It is normally a lack of B12 and iron that can leave you feeling cold, as being deficient in these nutrients can lead to some of the issues we have mentioned above.

B12 can be found in chicken, eggs and fish, whereas iron is best found in green vegetables, such as spinach, beans or broccoli. According to Health, a regular intake of these vitamins can help you stay warm but also prevent issues such as hypothyroidism and anaemia. Dr Holly Phillips, the author of The Exhaustion Breakthrough, says “Iron is a key mineral that helps your red blood cells carry oxygen throughout your body, bringing heat and other nutrients to every cell in your system”.

How can I stop feeling cold at night?

If you’re concerned you may be affected by any of the above conditions, talk to your doctor about the best treatments. In general, it’s best to arm your immune system by taking regular vitamins and improving your lifestyle. Certain issues, like a blood vessel disorder, can be lessened by quitting smoking. Also, ensuring you are at a healthy weight will help you maintain a good temperature overnight.

If you are healthy but still struggling to sleep at night due to feeling cold, try adjusting your surroundings:

  • Set your heating to a timer which will turn off overnight
  • Consider wearing socks to bed
  • Have a warm bath before bed
  • Take a hot water bottle to bed with you

 

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