Second Sleep – Rediscovering the Forgotten Sleep Pattern

Second Sleep – Rediscovering the Forgotten Sleep Pattern for Health and Longevity

Before the Industrial Revolution, many people slept in two nightly segments: a first sleep, a quiet waking period in the middle of the night (1–3 hours), and then a second sleep. Historical sources and laboratory studies suggest that this pattern can emerge spontaneously when evening light diminishes and nights are long. In today’s bright, schedule-driven world, we usually sleep in a consolidated “eight-hour block,” but for some individuals, a segmented approach may be worth exploring.

What is “Second Sleep”?

“Second sleep,” or segmented sleep, refers to a natural two-part sleep pattern: you fall asleep at bedtime (first sleep), wake calmly sometime around midnight (“mid-night waking”), remain awake for a while, and then return to sleep (second sleep) until dawn. Historian A. Roger Ekirch has shown that the terms first sleep and second sleep were widely used in European sources up until the 19th century.

Why Did the Two-Part Night Disappear?

Three factors are often highlighted:

• Electric light: Bright, extended evenings delay sleep pressure and compress the night into one block.

• Industrial work schedules: Fixed shifts required early mornings, leaving little room for a midnight pause.

• Cultural norms: “Eight hours straight” became the ideal in sleep hygiene and popular culture.

Ekirch’s work suggests that our modern consolidated sleep ideal is relatively new in human history.

The Biology Behind It: How Darkness Shapes Sleep Architecture

In controlled studies where healthy participants were given long nights with extended darkness (short photoperiods – e.g. 10 hours light / 14 hours dark), two symmetrical sleep blocks often appeared, separated by a calm waking period. These results suggest that when we don’t “compress” the night with artificial evening light and late habits, a segmented pattern may emerge naturally.

Nordic angle: Long winter nights in regions like Sweden (December–January) could, in theory, favor a more segmented pattern due to the short photoperiod. (This is a reasonable interpretation of photoperiod studies, not a clinical recommendation.)

Do Segmented Sleep Patterns Still Exist Today?

Yes. Around the world, bi- and polyphasic patterns are common, often in cultures with siesta traditions. For example, in one study from Oman, biphasic (afternoon siesta) sleep was the most common, followed by polyphasic, and then monophasic. This shows that “one single night block” is not universal.

Health: What Do We Know – and Not Know?

• Laboratory evidence: During extended dark periods, two-part sleep can emerge without impairing function – it seems to be a possible “normal state,” not necessarily a problem.

• Epidemiology (siesta/napping): Findings are mixed; some data link short naps or short total sleep to higher cardiovascular risk – associations likely influenced by lifestyle and health status (cause-and-effect is complex).

• Debate and nuance: Newer historical reviews caution against oversimplification. Consensus: the pattern existed, but varied widely by class, season, and region.

Segmented sleep is possible and sometimes natural – but it’s not a magical solution or a requirement for good health.

Who Might Benefit from Trying It?

• “Mid-night awakeners”: If you often wake around 2–3 AM and feel stressed about “needing to sleep,” allowing a calm wakeful period can reduce anxiety and improve the overall sleep experience. (Tip: keep this period quiet and low-stimulation.)

• Creative/spiritual practices: Historical sources describe prayer, reading, or quiet work during night watch. A peaceful “wakeful island” can be used for reflection – provided it doesn’t cut into total sleep.

• Not ideal if: you struggle with severe insomnia, have depression/anxiety that worsens at night, or live with strict schedules (e.g. small children, shift work) where regularity matters more than experimentation.

How to Try Second Sleep – A 14-Day Protocol

Goal: 7–9 hours of total sleep split into two blocks, with a calm midnight period (1–2h).

1. Dim lights 2–3 hours before bed. Use warm light, lower brightness, avoid strong screens.

2. Early bedtime: 8:30–9:30 PM during the test period.

3. Accept mid-night wakefulness: If you wake between 12:30–2:30, get up calmly or stay in bed. Choose low-stimulation activities: reading paper books, meditation, journaling, gentle stretching. Avoid strong light, screens, or email.

4. Second sleep: When sleepiness returns, go back to bed and sleep until your planned wake time.

5. Consistency: Keep the same schedule daily (including weekends).

6. Track results: Note total sleep, energy, focus, mood, awakenings, and whether night-waking anxiety decreases.

7. Adjust: If the wake period is too long (>2h), shift bedtime 15–30 minutes later or reduce evening light.

8. Stop if daytime fatigue persists for several days or if anxiety worsens.

Tips for biohackers: Keep the bedroom cool (17–19 °C), blackout curtains, morning daylight exposure (or a light lamp in winter), caffeine before noon only, minimal alcohol. Some find magnesium or glycine calming (individual response varies). (General tips – not medical advice).

Is second sleep “better” than one solid block?

Not necessarily. The key point is that segmented sleep can be natural and work well for some – especially if you already wake up at night.

How long should the wake period be?

Historically 1–3 hours. Practically: 45–120 minutes – keep it quiet and dark so drowsiness can return.

Can I replace “second sleep” with a siesta instead?

That becomes more bi-/polyphasic. Some cultures do this, but ensure total sleep is sufficient and that daytime naps don’t disrupt night sleep.

Is napping dangerous for the heart?

Not inherently. Some studies show links between short naps/short sleep and cardiovascular risk – associations, not proof of causation. Listen to your body and consult your doctor if you have heart disease.

Can second sleep help with insomnia?

If your “insomnia” is mainly worry about waking naturally at night, reframing it as segmented sleep may reduce stress. For severe insomnia, professional evaluation and evidence-based methods (e.g. CBT-I) are recommended.

Second Sleep is not a trend – it’s a historically and biologically plausible sleep pattern that some people may thrive on, especially if they already wake at night. Test it systematically, keep lights low, prioritize total sleep time – and choose the pattern that gives you the most energy, focus, and wellbeing.