Sleep quality outweighs duration for assessing psychological, physical health

Sleep quality is a stronger indicator of psychological and physical health than sleep duration, according to a recent Singapore study.

“By examining sleep duration alongside with sleep quality and their relationships with health statuses from the same population, the current study may be able to provide some form of comparative evidence to determine which of these two sleep indicators may be more important for public health, based on independent associations,” researchers said.

The current analysis included 6,126 community-dwelling adults (aged ≥18 years; 50.4 percent female) who participated in the 2016 Singapore Mental Health Study. Both past-month poor sleep quality (vs good sleep; odds ratio [OR], 1.6, 95 percent confidence interval [CI], 1.3–2.0), and short sleep (≤6 vs 7–8 hours per day; OR, 1.4, 95 percent CI, 1.1–1.7) were correlated with an excess risk of chronic pain. [PLoS One 2020;15:e0235816]

Disaggregating into the individual pain symptoms showed that short sleep duration was correlated only with migraine headaches (OR, 1.6, 95 percent Cim 1.2–2.2; p=0.002), while poor sleep emerged as an indicator of both migraines (OR, 1.8, 95 percent CI, 1.3–2.4; p<0.001) and back problems (OR, 1.4, 95 percent CI, 1.1–1.9; p=0.018).

Overall, impaired sleep quality was correlated with a greater likelihood of having any physical disorder (OR, 1.4, 95 percent CI, 1.1–1.7).

Similarly, the researchers found sleep quality to be a stronger predictor of mental disorders than sleep duration. Short vs long sleep duration was significantly predictive of both lifetime (OR, 1.6, 95 percent CI, 1.0–2.5) and 12-month (OR, 2.0, 95 percent CI, 1.2–3.3) obsessive-compulsive disorder (OCD).

In comparison, poor vs good sleep quality was  correlated with an elevated risk of having any mental disorder (lifetime: OR, 2.2, 95 percent CI, 1.7–2.8; 12-month: OR, 3.2, 95 percent CI, 2.3–4.3) and developing major depressive disorder (lifetime: OR, 2.0, 95 percent CI, 1.4–2.9; 12-month: OR, 3.1, 95 percent CI, 1.8–5.4), bipolar disorder (lifetime: OR, 2.8, 95 percent CI, 1.5–5.2; 12-month: OR, 4.2, 95 percent CI, 1.8–9.4), and generalized anxiety disorder (lifetime: OR, 2.3, 95 percent CI, 1.2–4.4; 12-month: OR, 4.3, 95 percent CI, 1.8–10.5).

As with sleep duration, impaired sleep quality likewise amplified the lifetime (OR, 2.2 95 percent CI, 1.4–3.4) and 12-month (OR, 2.4, 95 percent CI, 2.4, 95 percent CI, 1.4–3.9) risks of OCD.

The researchers also pointed out that they observed no U-shaped interaction between sleep duration and any of the health indicators. This suggests that only short sleep, not excessive sleep, bore adverse effects on both physical and psychological health.

“Our findings indicated that sleep quality may be a more important indicator for psychological and overall health compared to sleep duration,” they said. “Poor sleep quality combined with short sleep was associated with the highest number of morbidities and hence, there is a need for public awareness on the relationship between sleep and health.”

Future longitudinal studies are needed to better elucidate the directionality of interactions between the tested variables, they added.