Can sleep be “banked”? A PRO-CON debate

The question of whether humans can sleep more than is immediately necessary has practical relevance for several professions, particularly those requiring extended wakefulness. Should healthcare workers sleep longer before a 24-hour shift? Should soldiers maximize sleep before prolonged military operations? How should professional athletes schedule rest for optimal performance?

This PRO/CON debate is relevant to these questions. The PRO side, drawing on three key studies [1–3] argues that extending sleep can yield later benefits. The CON side, reinterpreting those studies and other [4,5], disagrees. Both camps employ metaphors to frame their positions. The PRO camp describes “sleep banking,” likening it to depositing money in a savings account for later use—except the “currency” is measured in sleep-dependent resources [6].

The CON camp challenges this analogy [7], offering two alternatives. First, they compare sleep to a credit card: one can temporarily “borrow” wakefulness by reducing sleep, but the debt must eventually be repaid. Second, they liken sleep to a gasoline tank: the tank has a finite capacity, and while it must be refilled when empty, it cannot be overfilled to extend future range.

Both sides present thoughtful arguments. However, the debate is hampered by an incomplete understanding of sleep’s fundamental function. Both camps agree that deeper insight into why animals sleep is necessary to determine whether “sleep banking” is possible, and if so, how it might be optimized.

Aside from rare dissenting views [8], there is a broad consensus that sleep is essential for survival [9,10] and well-being. Sleep has been documented in every species studied in detail, across at least six phyla (Chordata, Arthropoda [11], Mollusca [12], Nematoda [13], Cnidaria [14], and Platyhelminthes [15]). Importantly, many of the molecular mechanisms underlying sleep are conserved, suggesting that sleep evolved early in life’s history on Earth. The persistence of sleep on Earth despite its costs makes a strong case that sleep offers a core conserved function across phylogeny [16].

If sleep’s function were understood, researchers could test the concept of sleep banking at the cellular and molecular level. Animal models should be used to gain experimental power. Of relevance to this PRO/CON debate, one group tested in mice whether extending sleep via chemogenetic activation of a sleep-promoting brain center affected subsequent sleep following completion of the activation [17]. Another group, using Drosophila, showed that following thermogenetic sleep induction, there was a reduction in sleep, in a process the authors termed “negative sleep rebound” [18].

Current theories of sleep function fall largely into two categories: those that emphasize metabolic regulation and those that focus on changes within the nervous system. Comparative physiology provides a growing body of evidence across phylogeny for evaluating these metabolic and neural plasticity possibilities. Such comparative studies can inform this PRO/CON debate.

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