Most adults need 7–9 hours of sleep, but many people treat six hours like it’s close enough. In this episode of Night Shift, Justin breaks down why seven hours is the minimum, why eight is a better target, and how sleeping only six hours can affect your brain, mood, memory, metabolism, immune system, appetite, and discipline.

Tonight’s reminder: six hours is not a badge of honor. It’s a debt your body will eventually collect.

Source notes

The adult sleep recommendation of 7+ hours is supported by the CDC and the AASM/Sleep Research Society consensus statement.

The CDC notes that sleeping under 7 hours is associated with obesity, diabetes, high blood pressure, heart disease, stroke, frequent mental distress, and mortality.

The cognitive-performance claim comes from Van Dongen et al., which found chronic restriction to 6 hours or less produced cumulative deficits comparable to up to two nights of total sleep deprivation.

The memory claim is supported by a 2024 meta-analysis finding that sleep restriction of 3–6.5 hours impaired memory formation compared with 7–11 hours.

The immune/cold claim comes from Prather et al.; people sleeping 6 hours or less had about a fourfold higher cold risk after viral exposure than those sleeping more than 7 hours.

The appetite claim is supported by Spiegel et al., which found short sleep associated with lower leptin, higher ghrelin, and increased hunger/appetite.