Why the Time You Go to Sleep Really Matters

In today’s busy world, many people stay up late to finish tasks or scroll through their phones—often ignoring the impact of sleep timing. According to Dr. Saurabh Sethi, a California-based gastroenterologist, going to bed past midnight can harm your physical and mental health, even if you get a full eight hours.

Our bodies follow a natural circadian rhythm. When this is disrupted by late bedtimes, hormone regulation, digestion, and brain function suffer. Deep and REM sleep, which are vital for healing and memory, typically happen earlier in the night. Delaying sleep means missing these stages.

Staying up late can raise stress hormone (cortisol) levels, increase appetite, and lead to weight gain due to changes in leptin and ghrelin. It also impacts mood, increasing the risk of anxiety or depression. Over time, late bedtimes can lead to fatigue, poor focus, and brain fog.

Dr. Sethi recommends sleeping between 9:30 and 11:00 PM to align with your body’s natural rhythm. This helps restore energy, improve mood, and protect heart and immune health. Remember: when you sleep is just as important as how long you sleep. Small changes in sleep timing can lead to big health improvements.