A sleep problem is not only difficulty sleeping at night—it is sleep quantity/quality that impairs daytime function. Signs include waking unrefreshed, daytime sleepiness, attention and memory issues, irritability, low energy, increased mistakes/accidents, headaches, and heavy reliance on caffeine. Nighttime clues include prolonged sleep-onset, frequent awakenings, early awakening, loud snoring, breathing pauses, gasping awakenings, leg restlessness, nightmares, or parasomnias. A practical threshold: symptoms at least 3 nights/week for ≥1 month (especially ≥3 months) plus daytime impairment warrants evaluation. A 1–2 week sleep diary can clarify behavioral, circadian, or medical patterns. Snoring + sleepiness suggests sleep apnea; leg discomfort suggests RLS; early awakening with low mood can be linked to depression. Evidence base: clinical frameworks describing sleep-disorder symptom patterns and evaluation; chronic insomnia definitions and management principles.