Sleep hygiene refers to the behaviors and environmental conditions that support healthy sleep. The bedroom should be cool, dark, and quiet: a temperature of 60 to 67 degrees Fahrenheit (15.6 to 19.4 degrees Celsius) helps the body achieve the natural drop in core temperature that precedes sleep. Darkness supports melatonin production and prevents the awakening effects of light, while quiet reduces arousals during the night. Comfortable bedding, including a supportive mattress typically lasting 7 to 10 years, and a pillow matched to one's sleep position complete the setup. Side sleeping is most common and generally easier on the back and airway, while stomach sleeping is hardest on the spine. Many people sleep best with cool ambient air and warm bedding layered on top.
Light at night is particularly disruptive because of its melatonin-suppressing effects. Blue light, with its short wavelengths, is especially potent in this regard, which is why experts recommend avoiding screens for 1 to 2 hours before bed or using night-mode filters. A warm bath about 90 minutes before bed can also help: the subsequent cooling of the body as it leaves the warm water aids the natural temperature drop that initiates sleep.
Beyond the bedroom, daily habits matter greatly. Caffeine blocks adenosine receptors and reduces deep sleep, so timing its use is critical. Alcohol, while initially sedating, disrupts REM sleep and fragments sleep later in the night, and nicotine is a stimulant that harms sleep onset and quality. Exercise generally improves sleep, though intense late-evening workouts may interfere for some, and morning or afternoon sessions are usually best. Heavy or spicy meals close to bedtime can disrupt rest, while light snacks may help. Adequate hydration supports sleep, but excessive fluid intake causes nocturia, or nighttime waking to urinate. Across all of these factors, the most powerful contributor to good sleep is consistency, since predictable timing and routine align the body's clock more than any single environmental adjustment.