For some women, one isn’t just the loneliest number – it’s also the most depressing.People who live alone are much more likely than others to take antidepressant medications, according to a highly publicized 2012 7-year study of nearly 3,500 working-age adults by the Finnish Institute of Occupational Health.“About 1 in every 4 women living alone had purchased antidepressants versus only 1 in 10 women not living alone,” says lead author Laura Pulkki-Råback, PhD, a researcher and lecturer at the University of Helsinki’s Institute of Behavioral Sciences.Some people who live alone feel lonely – and that may play a key role in depression, says social psychologist Matthew Zawadzki, PhD, a postdoctoral scholar at Penn State in Philadelphia, who led a recent study on the effects of loneliness in college students.“My research showed that people who were lonely reported having a more depressed mood and worse sleep quality,” he says.Other studies have linked loneliness to lower self-esteem, higher blood pressure, poorer immune functioning and an increased risk of dementia in later years.Social isolation even hastens death in middle-age and older adults, according to a 2013 study by University College London in England, published in the Proceedings of the National Academy of Sciences.At the same time, more people than ever are living alone. Of all U.S. households, 27% are one-person households, with women making up slightly more than half of those, according to the 2010 U.S. Census, the last one conducted. By comparison, singles constituted only 18% of households in 1970.

Invite your friends to meet for dinner or go on an outing, and offer to make arrangements.Reciprocate invitations. No need to throw a big party; having a few people over for snacks, a movie or game night is an easy way to maintain relationships.Organize an all-ages activity for your extended family, such as a picnic in the park or day at the zoo.Look through your phone contacts, and call one person whom you haven’t spoken with in the last month.Do something that’s helpful and rewarding: For example, volunteer to babysit for nieces, nephews or grandkids. Or offer to spend a few hours with an aging relative whose caregiver could use a break.

If your home seems too quiet, play background music. But don’t leave the TV on all day; it draws your attention away and forces your brain to work at sorting out the different sounds, which may increase stress.Consider adopting a dog or cat, if you enjoy having a pet and can accommodate one. Pet ownership significantly decreased loneliness in older women, according to a 2012 study published in Geriatric Nursing.Make a list of people to call when you just need to hear a friendly voice.

If negative thoughts keep you awake, consciously replace them with innocuous ones. “I read right before bed, so I’ll think about the characters in the story as I drift off to sleep,” LeRoy says.Add extra pillows to your bed to make it feel cozier, warmer and less empty.If you don’t fall asleep within half an hour, get up and do something that occupies your thoughts. Write in a journal about whatever’s troubling you for a few minutes, and then try to get to sleep again, LeRoy suggests.

Feeling sad, empty or irritable almost all the timeLosing interest in things you once enjoyedFeeling helpless or hopelessHaving trouble getting out of bedSleeping too much or too littleOvereating or losing your appetiteHaving trouble paying attention or making decisions