Scientists are testing the “surprising theory” that “splitting sleep into two separate blocks” may be “the most effective sleep pattern for people working through the night”, said the BBC.
Better management of insomnia
Biphasic sleep means two distinct sleep periods in 24 hours instead of one. Researchers suggest it may be a more natural rhythm, even if the biological reasons for it are still being debated.
The concept has “captured the interest of many today”, said MediaFeed, and some individuals are “experimenting with segmented sleep patterns”. Its supporters say the benefits include “improved restfulness and better management of insomnia”.
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During pre-industrial times people often slept in two blocks. Roger Ekirch, a historian at Virginia Tech, found that sleeping in two halves was the “predominant pattern” in the Western world until the mid-19th century. A “typical family” would “go to bed around nine, wake naturally after midnight for an hour or so – for prayer, chores, conversation – then sink back into what they called their ‘second sleep’.”
This changed when artificial light transformed the “economics of the night” and gas lamps “began lighting London’s streets in 1807”. As a result, “people stayed up later, the gap between the two sleeps narrowed and eventually closed”.
‘Dubious’ findings
The shift to a single period of sleep came at the time of the Industrial Revolution, as people changed to new work schedules, which were dictated by “mechanised time”, said MediaFeed.
But Ekirch believes the old approach hasn’t fully disappeared because the prevalence of “middle-of-the-night insomnia” represents a “persistent echo, a relic of this earlier pattern of sleep”.
A study in 1992 sought to discover whether, without industrialisation, humans would have remained natural biphasic sleepers. It limited participants to just 10 hours of light per day and found that they naturally shifted into a biphasic sleep pattern.
But the experiment drew criticism. In 2023, Niall Boyce wrote in the journal Medical History that its findings were “dubious” and suggested participants were simply restless.
Disrupted sleep, whether by working night shifts or insomnia, does have health implications. When we sleep, “our brain consolidates the memories of the day, processes emotions, and solves problems that defied it in the waking hours. It also strengthens immune defences and repairs muscle tissue”, said the BBC
So for those struggling to get enough sleep, “it’s not solely about being tired, but potentially about repeatedly disrupting a system that's doing far more behind the scenes than many people realise”.
Some experts have warned that biphasic sleep could have health risks, including from disruptions to circadian rhythms. Existing research on the topic is “fragmented” because some studies treat biphasic sleep as “one long sleep plus a brief nap”, but others “count only two equal periods”, so there is “no agreed definition”.
