Why do some people need more sleep than others?

Sleep needs vary primarily due to genetics. Certain gene variants, like those affecting the ADRB1 and DEC2 genes, can make some people naturally function well on less sleep while others genuinely require more. Age also plays a major role, with children and teenagers needing significantly more sleep than adults due to brain development. Beyond genetics, factors like overall health, stress levels, physical activity, and whether someone has accumulated sleep debt all influence how much rest a person needs. People recovering from illness or intense exercise typically need more sleep for tissue repair and immune function. Mental health conditions like depression can also alter sleep requirements. Essentially, sleep need is a complex trait shaped by biology, lifestyle, and circumstance.