The link between anxiety and sleeplessness is a long-established one, but researchers only just started to understand how it works and why. Studies in 2017 and 2018 located specific areas of the brain that "fire" when you're anxious, and those cells have effects on other parts of your behavior — like your sleep. A 2017 study found that a part of the amygdala, a section of the brain that's related to stress and anxiety, could "turn on" suddenly in anxious mice while they were deeply asleep, waking them up or disturbing them.

In 2018 scientists found that the hippocampus, which translates experiences into memory while you sleep, also contains anxiety cells. So if you're up at night worried about how you're going to host 17 people for Thanksgiving, it may simply be that your anxiety neurons are dancing around like visions of sugar-plums.

Anxiety also does something else to the brain: it impacts its plasticity, or ability to adapt physically to new stimuli. Anxiety makes our brains incapable of learning that something is safe and secure, even if we've done it a million times, and reacts to it like a new threat every time. This is why, say, if someone has flight anxiety, they'll still worry about mechanical failure even though they've flown safely every single holiday season.

A study in 2016 showed that in anxious people, the brain retains its "plasticity" — its preparedness for new things — even when doing something for the thousandth time. If something made you anxious five years ago, it might well make you anxious now, because of the brain's wiring.

Feeling like you can never get quite comfortable with the temperature at your aunt's house isn't necessarily just down to the thermostat. Anxiety attacks are associated with feeling colder and having cooler skin, because anxiety constricts blood vessels and stops warm blood flowing to the body surface. Anxiety may also speed up your metabolism, making your body feel hotter — and a disorder that's been the target of new interest in the past few years, called psychogenic fever, shows up when your body translates stress and anxiety into feverish temperatures.

Winter and cooler weather in general is associated with asthma attacks, though not as strongly as fall and spring, with their high pollen counts. But if you experience more asthma attacks over the holidays, anxiety may be to blame. Stress is considered a big trigger for asthma because anxiety changes breathing patterns to make the body ready to deal with threats, and that shift can cause asthma attacks to occur.

Yep, anxiety can affect your ears, whether you're traveling or not. The Anxiety Center notes that ear popping and ear pressure issues are a known anxiety symptom, because stress seems to have an affect on ear pressure in some people; tinnitus, or ringing in the ears, is known to become worse when people are anxious, according to the British Tinnitus Association.

As the inner ear plays a crucial role in keeping us balanced, you may also find that anxiety over the holidays makes you dizzy, brings on vertigo or induces weird feelings of sea-sickness.

Anxious yawning may seem like an odd physical response, but the experts at Calm Clinic explain that yawning when you're anxious is pretty natural. "When you hyperventilate, your body starts to feel like it's not getting a full breath. As a response, it tries to yawn, because yawning expands the rib cage and sends a signal to your brain that you did indeed get a full breath. In that sense, yawning is trying to tell your body to relax," they write. If you're yawning all over the place but don't feel tired, this may be why.

An interesting neurological consequence of anxiety? Impulsive behavior. You'd think that feeling anxious would mean people made conservative decisions, but not so; the Calm Clinic points out that impulsivity can be brought on by anxious desperation or panic. Research in 2016 found that anxiety impedes activity in the prefrontal cortex, which is responsible for our decision-making and helps us weigh pros and cons. The anxious brain can't process decisions in standard ways — which is why you panic-bought 15 singing Santa ties on Christmas Eve.

Holiday anxiety is a real thing, though it can be difficult to talk about when everybody is focused on having a good time. If you notice these physical symptoms during the holiday period, it's a good idea to look into anxiety-busting techniques like mindfulness, and talk to a GP or therapist about how to help yourself manage stressful events. And remember, the holidays may come every year, but the season is temporary — and it's only a few short weeks until the days start getting longer again.