Why Permanent Daylight Saving Time Might be a Bad Idea for Your Health

You Should Know: When clocks fall back tomorrow, evenings will get darker earlier. If you wish we could keep that evening light year-round, there may be a trade-off: Our internal clocks rely on light, and experts say permanent daylight saving time could mean darker winter mornings, potentially disrupting circadian rhythms that regulate sleep, hormones and metabolism.

Going Deeper: Morning light helps synchronize our internal body clocks, while evening light can delay the release of melatonin, which helps regulate sleep. The American Academy of Sleep Medicine argues that permanent DST could worsen this mismatch by creating darker mornings and brighter evenings. Research also suggests that permanent DST could lead to declines in heart health and sleep deprivation in teens.

On the other hand, dark winter evenings can feel draining, and seasonal affective disorder (SAD) is a recognized form of depression associated with seasonal changes. More evening daylight could make it easier to spend time outdoors after work. But the evidence doesn’t suggest that permanent DST would improve mental health. A 2026 systematic review of 157 studies found no clear, consistent effects on psychiatric outcomes.

Takeaway: Sleep experts generally favor permanent standard time because it better aligns daylight with our body clocks. 

Bottom Line: The evidence isn’t definitive, but getting regular morning light and keeping a consistent sleep schedule can help whichever way the clocks go.