Why one long sleep may not suit everyone, researchers argue

Sleep scientists are increasingly questioning the assumption that a single unbroken block of seven to nine hours is the ideal for everyone, according to a review reported by Sujata Gupta for Science News.

Segmented sleep – combining a core period of night-time rest with one or more naps – is already common practice for many groups, including shift workers, teenagers, new parents, older people and those going through menopause.

In Oman, for example, many people rise before dawn for prayers and return to sleep or nap later in the day, said sleep researcher Mohammed Al-Abri of Sultan Qaboos University.

Despite how widespread such patterns are, most sleep research has focused on single-block sleep, according to a review published in Brain Medicine in August. A separate review in Sleep Health argues that naps themselves need to be studied with more nuance, since factors such as duration, timing and frequency vary considerably and have produced conflicting findings on whether napping helps or harms health.

Segmented sleep is not a new phenomenon. Historian A. Roger Ekirch has documented a “two-sleep” pattern common in medieval Europe, in which people slept from dusk, woke for a period of activity in the night, then slept again until sunrise – though this model sits awkwardly with a modern world of artificial light and late-night screen use.

Evidence on whether long naps are beneficial remains mixed. Afternoon naps longer than an hour have been linked to higher risks of obesity and elevated blood sugar, prompting Al-Abri to recommend naps of under 30 minutes.

However, a small study of elite Australian soccer players found that longer naps of one to two hours could aid recovery and performance, with nap length affecting the balance between deep sleep and REM sleep.

Genetics may also play a role: a study of over 1,200 Spanish participants found that people who napped in a way that matched their genetic predisposition faced no increased obesity risk, while those who went against it did.

Researchers broadly agree that sleep advice should move away from one-size-fits-all guidance and towards more personalised recommendations that account for individual circumstances, including work patterns, genetics and lifestyle.