Sleep hygiene is the unglamorous foundation of good sleep. Unlike specific interventions like meditation or supplements, sleep hygiene encompasses the daily habits and environmental factors that determine whether your sleep succeeds or fails. Proper sleep hygiene alone resolves many sleep complaints without any more sophisticated treatment. The challenge is that sleep hygiene requires consistency, not intensity—a little attention every day beats sporadic heroic efforts. Consistent sleep and wake times serve as the most critical sleep hygiene factor. Your circadian system expects regularity and performs best when given it. Weekend vs. weekday shifts confuse your clock and create the social jet lag discussed elsewhere. The goal: same sleep and wake times within 30 minutes, 7 days per week. This single rule, followed consistently, improves sleep more than any other single behavioral change. The sleep environment should support the biological transitions sleep requires. Darkness signals nighttime to your suprachiasmatic nucleus; even small amounts of light suppress melatonin. Complete blackout curtains or a quality sleep mask create the dark your biology expects. Cool ambient temperatures (65-68°F) allow the core temperature drop that triggers sleep onset. Quiet environments prevent acoustic arousals; white noise or other consistent masking sounds handle unavoidable noise. Caffeine clearance requires planning. With a 5-6 hour half-life, caffeine from afternoon coffee remains active well into evening hours. Even if you can fall asleep with caffeine in your system, it reduces sleep quality by blocking adenosine clearance. Set a firm afternoon cutoff—12 hours before bedtime if you're sensitive, 6-8 hours if you're a fast metabolizer. Similarly, alcohol disrupts sleep architecture; while it may help sleep onset initially, it fragments second-half sleep as it metabolizes. Exercise timing affects sleep through multiple mechanisms. Morning exercise anchors circadian timing and creates morning light exposure. Evening exercise raises body temperature and can interfere with sleep onset if too close to bedtime—but this effect varies by individual. Generally, complete exercise cessation 2-3 hours before bed allows body temperature to normalize. Exercise also increases sleep pressure through adenosine accumulation, which generally aids sleep onset if not too close to bedtime. The winding-down period matters more than most people appreciate. The final hour before bed should involve progressively calming activities—dimming lights, putting away screens (or using blue light filters), reading or gentle stretching. This period allows cortisol to decline and melatonin to rise without interference. Jumping from intense activity—work, exercise, exciting entertainment—directly into bed often fails because your nervous system hasn't transitioned to sleep mode. Daytime light exposure provides the circadian anchor that makes nighttime sleep possible. Get morning light, especially in early hours after waking, to set your circadian clock. Aim for 20-30 minutes of outdoor light exposure in the morning, or at minimum, bright indoor lighting near windows. This single factor may be more important than any evening intervention, because it establishes the timing that makes everything else work.