Most of us have heard again and again that getting enough sleep is one of the most important things we can do for our health, and that eight hours is the gold standard.
Few people stop to ask whether more sleep is always better.
A meta-analysis of 79 cohort studies was published in GeroScience in March 2025.
It found that adults who regularly slept more than 9 hours a night had a 34% higher risk of dying from any cause than those sleeping 7 to 8 hours.
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Short nights carried a smaller penalty. People who typically slept under 7 hours faced a 14% higher risk of death during follow-up.
The pattern was stronger in women. Those who clocked 9 hours or more had a 44% higher mortality risk compared with women who slept 7 to 8 hours.
Long sleep
The authors are cautious about causality.
They write that extended sleep may be a signal of hidden health problems rather than a direct cause of early death.
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Chronic illnesses that remain undiagnosed, or things like metabolic trouble, can quietly push someone to spend more hours in bed.
A separate systematic review in Cureus in January 2025 reached a similar conclusion.
People sleeping more than 9 hours a night showed higher rates of coronary artery disease, stroke, heart failure and high blood pressure.
The Cureus authors flagged elevated inflammatory markers in long sleepers.
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They also noted that heart disease itself can nudge people toward longer nights through fatigue and medication effects.
The 7 to 8 hour window still holds up
The Centers for Disease Control and Prevention recommends adults aged 18 to 60 get at least 7 hours of sleep each night.
For adults aged 61 to 64 the range is 7 to 9 hours, and for people aged 65 and older it is 7 to 8 hours.
In the GeroScience analysis, the 7 to 8 hour group was the reference point, meaning everyone else was compared against it.
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Both ends of the curve, too little and too much, were tied to a higher chance of dying during follow-up.
When extra sleep is a red flag worth checking
If you regularly sleep more than 9 hours but still wake up tired, the length may be masking something treatable.
Loud snoring, daytime sleepiness, morning headaches or waking up gasping can point to obstructive sleep apnea.
Depression, an underactive thyroid, anemia and some chronic infections can also show up as a sudden pull toward longer sleep.
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A persistent change in how much sleep your body seems to need is worth raising with a doctor, especially if it comes with other symptoms.
This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.