As the social neurologist John Cacioppo and his team at the University of Chicago discovered, the feeling of loneliness — the subjective experience itself, not the bare fact of being alone — brings about hypervigilance to social threat. This state, which is entered into unknowingly, makes the lonely person far more alert to signs of rejection or exclusion than those of warmth or friendliness. It’s a vicious circle, in that each misreading of social nuance becomes evidence for further withdrawal, causing loneliness to become steadily more entrenched.

Because hypervigilance is entered into invisibly, it has to be consciously recognized and corrected. In the current circumstances, most social encounters are likely to happen on the internet or by phone. Perhaps a tweet isn’t liked, or a message is read but not replied to, the blue tick inflaming the sense of going unregarded. Rather than jumping to alarmed conclusions about being left out or disliked, it’s vital to remember that a bias is occurring, and to keep maintaining and participating in social contact.

Part of the reason the current crisis is so frightening is that it sets off a fear not just of being in quarantine but also of being abandoned altogether, the nightmare of the social animal. This is what lies behind all those empty cities in science fiction films: the terror of being the last one left, patrolling deserted grocery aisles, like a desolate, despairing Will Smith in “I Am Legend,” the resources running out, no one left to love. This feeling is profoundly isolating to experience and yet it’s also a point of connection with billions of strangers. One of the hardest things to grasp about loneliness is that it’s a shared state, inhabited by a multitude at any time. Whatever anxiety you’re experiencing right now, you’re not alone. Everyone is frightened of being left behind.

The need for connection is so central to our being that to experience its lack plunges the body into a state of minor emergency, driving up cortisol and adrenaline and contributing to a feeling of what for most people will already be peak anxiety. There are antidotes, from simple breathing exercises to deliberately noticing small pleasures in the physical environment: a budding leaf, a cloud, the taste of toast. The natural world continues, and paying attention to it is a way of grounding terror — remembering that whatever else may happen, spring is on the way.

But loneliness isn’t just a negative state, to be vanquished or suppressed. There’s a magical aspect to it too, an intensifying of perception that led Virginia Woolf to write in her diary of 1929: “If I could catch the feeling, I would: the feeling of the singing of the real world, as one is driven by loneliness and silence from the habitable world.” Woolf was no stranger to quarantine. Confined to a sickbed for long periods, she saw something thrilling in loneliness, a state of lack and longing that can be intensely creative.