You can’t miss them when you walk around a city: shapeless masses pressed up against buildings or into corners. Homeless people sleeping outside, even now when the temperature is cold and dropping. The lucky ones preserve their body heat under a pile of blankets; others make do with cardboard boxes or layers of clothes.

Some die. About 700 a year in the United States. The solution seems obvious: their lives would be saved if they slept in the warmth of a homeless shelter. But there aren’t enough shelter beds to go around, and some of the beds that do exist come with very unappealing strings attached:

1. The “#1 Reason Homeless People Don’t Use Shelters [is the] Lack of Available Beds,” writes formerly homeless Kylyssa Shay. Shelters are over-crowded in many, if not most, cities. People must line up hours before the facility opens to secure a bed for the night, and go through the same process the next day and the next.

2. Those who hold jobs (and many homeless people do) can’t always be in line at 4:30 in the afternoon, so they cannot get a shelter bed. Those who choose to stand in line may give up on finding employment because of the schedule.

3. As if homelessness didn’t cause enough physical discomfort (hunger, untreated pain from medical conditions, often being dirty, carrying all of one’s belongings), shelters often add a couple, like bed bugs and body lice, which are inevitable when a different homeless person sleeps in a bed each night. Contagious diseases are also common among a population that lacks access to nutritious food and adequate medical care. Shelters don’t have the means to quarantine the ill from the general population, making a night in a shelter a health risk. Hepatitis and tuberculosis are particularly common.

4. Straddling the line between uncomfortable and life-threatening is the lack of shoes that fit. Shoe theft is a common problem for the homeless, and is particularly common in shelters. (Theft generally is not unusual.) Not having shoes, or having only shoes that don’t fit well, can cause wounds that make it challenging or impossible to walk, and there are precious few places in a city where a homeless person can recuperate for a while without having to move along.

5. A dog or cat is often a homeless person’s best friend and only family. For young women on the street alone, a dog can also provide indispensable protection. But shelters for homeless people rarely accept their companion animals. Many people prefer sleeping outdoors to giving up their beloved friends.

6. Some shelters close their doors to people who are under the influence of alcohol or illegal substances. This is an understandable rule that not surprisingly leaves some people who need shelter out on the street.

7. Nevertheless, some shelters are known as operation centers for drug dealers and are therefore considered dangerous. Some homeless people prefer their chances outside.

8. There are few family shelters that accept single fathers with children. Sometimes the solution is for the children to spend the night in the shelter while dad sleeps outside.

9. Lesbian, gay, bisexual and transgender (LGBT) people often face discrimination and “physical risk” in homeless shelters. For instance, transgender “women (born with male genitalia but identify and live as women) forced to take shelter with heterosexual men are frequently subjected to verbal, physical, and sexual abuse.” Some shelters simply deny entry to transgender people.

10. Some faith-based homeless shelters require guests to sit through sermons and even personal appeals to convert to their hosts’ religion. Enduring these sometimes derogatory, sometimes coercive tactics day after day is too much for some, especially people with strong religious convictions of their own.

You can do something to help end homelessness. The National Coalition for the Homeless recommends, “Get connected to a coalition. Volunteer at your local, state, or national housing or homeless advocacy coalition, or make a financial contribution to support their work. For the name of the coalition nearest you, see NCH’s Directory of National Housing and Homeless Organizations.”