Last week, my sister bought me a grey beanie. I’d never worn a beanie before so while it felt warm and looked pretty nice, I didn’t really know what to make of it. A few nights ago however, I was feeling quite cold so I decided to try it on. What happened next was amazing – within five minutes of wearing the beanie, my body was feeling super toasty. Naturally, the following thought came to me: “Beanies are a superior source of cosiness than tops and bottoms.” And as a graduate from a Biomedical degree, I knew I had to test this hypothesis.

So over the next few hours, I ran some extremely reliable experiments (N=1). These were the results:

Table 1. Cosy ratings under various clothing combinations. Heavy tops + bottoms defined by >3 layers of clothing. “–” = not wearing item, “+” = wearing item.

Trial	Beanie	Heavy tops + bottoms	Cosy rating (1 – 10)
1	–	–	1
2	–	+	5
3	+	–	8
4	+	+	10

As seen in Table 1, the results of the controls were as expected. Trial 1 (neg. control) demonstrated that in the absence of a beanie, heavy tops and bottoms, one feels cold. Trial 4 (pos. control) showed that when wearing a beanie, heavy tops and bottoms, one feels cosy. Given beanies and clothes provide insulation, these results are unsurprising.

Interestingly, the results further demonstrated that beanies alone (trial 3) give an increased cosiness rating compared to heavy tops + bottoms alone (trial 2). This supports the hypothesis that beanies are a superior source of cosiness.

But why? Well, despite the external environment typically varying between 0^oC to 40^oC, our bodies do a pretty good job at keeping our internal environment somewhere around 37^oC regardless of the outside temperature – a process called thermoregulation. However, thermoregulation is more effective in some parts of the body over others. For instance, the head doesn’t regulate its internal temperature very well compared to, say, the abdominal area. This observation is explained in an article from Harvard Health:

“But we’re not as thermostatically sensitive above the neck as we are below it. Blood vessels in the surface of the head constrict very little in response to cold, which is a good thing because the brain needs a steady supply of blood. There’s little subcutaneous fat for insulation. As a result, even if the rest of your body is nicely wrapped up, if your head is uncovered you’ll lose lots of body heat — potentially up to 50% of it — in certain cold-weather conditions. What’s more, a cold head can trigger blood vessel constriction in the other parts of the body, so it can make your hands and feet feel cold even if you are wearing mittens and warm socks and shoes.”

The solution? Wear a beanie to keep the outside of your head at a cozy temperature – this way, the head doesn’t need to work as hard to keep the internal environment at 37^oC. I was wondering how to make this realisation more profound but I can’t think of anything… so yeah, beanies!