Lighting runs your body clock harder than your alarm does. continue Sounds dramatic, but your brain reads brightness and color like a time stamp. Blue-rich light says "morning, get moving." Warm, low light says "wrap it up." Send the wrong signals and you'll be awake at midnight, wondering why your head feels like a floodlit stadium.
Morning: go bright
Sunlight is the strongest cue you can give. Ten to twenty minutes outside after waking beats any indoor bulb, even on a gray day. Cloud cover still delivers thousands of lux, far more than a typical living room. No yard? Pull the curtains wide and sit by the window with your coffee. If winter mornings are pitch black where you live, a bright daylight lamp on your desk can stand in.
Evening: keep it low
About two hours before bed, drop the brightness. Switch off overhead fixtures and lean on lamps. Pick bulbs around 2200 to 2700 kelvin, the amber glow of a candle flame. Many smart bulbs shift on a schedule, so the house slides toward sunset without you thinking about it. Cool white at ten at night is like espresso after dinner. Technically allowed. Probably a mistake.
Screens, the sneaky culprit
Phones and tablets pour blue-leaning light straight into your eyes from about a foot away. Night modes help a bit. Lower brightness helps more. Leaving the phone in another room helps most, although I know that's the toughest advice to swallow. A friend of mine bought an old-fashioned alarm clock for exactly this reason, and she says her evenings turned oddly long and pleasant.
Inside the bedroom
Keep it dark. Really dark. Blackout curtains do the job, and a sleep mask does too if you rent and can't hang heavy drapes. Cover tiny standby LEDs with a dab of tape. If you need a path to the bathroom, use a motion-activated nightlight in dim red or amber, mounted low on the wall, so you don't blast your eyes wide open at three in the morning.
If you work nights
Your schedule might fight the sun. Fine. Get bright light during your "morning," whenever that lands, and put on dark glasses for the commute home after a night shift. Tell your household that your bedroom is a cave during your sleeping hours. Be firm, be kind, bribe with snacks if needed.