Your question touches on a common and often controversial practice in urban design. Yes, the armrests on park benches are frequently specified with the explicit intent to deter people from lying down. This design strategy falls under the broader category of "hostile architecture" or "defensive design.
These armrests, often placed at intervals along the seating surface, physically segment the bench into individual seats. Their primary function shifts from providing arm support to imposing a sitting-only posture. For a person wishing to lie down, these protrusions become uncomfortable obstacles, making it nearly impossible to rest horizontally.
Proponents of this design, typically city officials or business owners, argue it serves several purposes: it discourages long-term occupancy by individuals experiencing homelessness, prevents benches from being used as beds, and aims to maintain accessibility for all intended users—like seniors or families who need a place to sit briefly. The goal is often framed as preserving public order and hygiene.
However, this approach sparks significant ethical debate. Critics condemn it as a form of "anti-homeless architecture" that addresses the symptom (visible homelessness) rather than the root cause (lack of housing and support services). They argue it creates exclusionary public spaces that are hostile to the most vulnerable, offering discomfort instead of compassion. The design essentially weaponizes everyday furniture to manage social issues.
Beyond ethics, there are practical considerations. Such benches can be less comfortable for everyone, including the elderly or those with certain disabilities who might benefit from being able to shift positions. The conversation is increasingly shifting toward seeking balanced solutions. Some cities are exploring "compassionate design"—providing supportive housing and dedicated safe rest spaces while designing inclusive public benches that are comfortable for sitting but not conducive to sleeping, perhaps through subtle curvature rather than aggressive armrests.
Ultimately, the specification of such armrests is a conscious design choice that reflects a community's priorities in managing its shared spaces. It sits at the complex intersection of urban planning, social policy, and human dignity.