Not sleeping at night may present as trouble falling asleep, frequent awakenings, or early-morning awakening. Short-term episodes are commonly tied to stress, jet lag, shift changes, illness, excess caffeine/alcohol, and poor sleep habits. If it persists beyond about a month, assess for drivers such as anxiety/depression, chronic pain, reflux, thyroid disorders, restless legs syndrome, and obstructive sleep apnea. Loud snoring, witnessed breathing pauses, morning headaches, and excessive daytime sleepiness raise suspicion for sleep apnea. Behavioral conditioning matters: repeated “trying hard to sleep” can increase anxiety and teach the brain that bed equals wakefulness. That cycle is a key reason CBT-I (stimulus control, sleep restriction, cognitive restructuring) works. A structured plan—fixed wake time, morning light, caffeine cutoff, reduced evening screens, and rebuilding the bed-sleep association—usually outperforms unstructured remedies. Evidence base: ACP recommends CBT-I first-line for chronic insomnia; Mayo Clinic summarizes causes/evaluation of sleep disorders; NHLBI/AASM outline diagnostic pathways for sleep apnea.