Biphasic sleep: the old custom making a comeback as a wellness trend

Biphasic sleep: the old custom making a comeback as a wellness trend

The latest wellness trend promises to reset your sleep: split it in two. Go to bed for two or three hours, stay awake for two hours in which you should be active, then sleep the rest. It is nothing new, even if its advocates sell it as a revolutionary discovery. What is new is seeing it as a healthy lifestyle, with smartwatches measuring the quality of each phase.

The historical precedent they don't tell you about on Instagram

The history of biphasic sleep is documented going back centuries. In the Middle Ages, it was common to speak of the "first sleep" and the "second sleep", with a waking interval in between devoted to praying, reading or socialising at night. Carthusian monks have kept this routine in their monasteries forever, dividing the night into two periods of prayer and rest. There are also references to Amazonian tribes that maintain similar patterns. The problem is that modern advocates tend to forget that those who practised it had rhythms of life very different from those of an office worker with a split shift and artificial light until the small hours.

Healthy, or only for those who don't have to get up early?

The most obvious criticism is that this pattern is only viable for those whose lives are sorted or who spend their time lounging around, as the debate puts it. For everyone else, who has to get up early for work, splitting your sleep is an impossible luxury. Moreover, some point out that the ancient philosophers and writers who praised waking up at night probably did so because they went to bed drunk and proge up hungover, not as a conscious health choice. The moment of minimum body temperature, around 6 a.m., makes it hard to fall back asleep if you have been active before, which can wreck the sleep cycle.

What if it's just a passing fad?

Like so many other fads — sun callus removal, extreme fasting, palaeolithic diets — biphasic sleep risks becoming a new fetish for the trendy and self-assured, with watches comparing the efficiency of each phase. Meanwhile, most of the population still sleeps in one go, and probably will keep doing so. With any luck, the fad will pass before someone tries to sell you a smartwatch specialised in biphasic sleep. Or maybe not: the wellness business never rests.