u/Silly_Slip_8359

As I dug into the research, it turned out that naps aren’t just good or bad for you—it depends on when and how long you take them. For example, in a 2021 meta-analysis, taking a short daytime nap had an overall modest effect on cognition, with an effect size of 0.18. That effect was stronger still for alertness specifically, with an effect size of 0.29—but only if those naps were early in the afternoon before 1 p.m., according to researchers.

Nap lengths weren’t as important, but there was some conflicting data related to the “sleep inertia” stage of wakefulness that occurs shortly after waking from a nap. One lab study showed no sign of sleep inertia within 15 minutes—even after naps lasting up to 60 minutes. Late naps, however, do tend to mess with your nighttime slumber, experts told me.

On the other end of the spectrum is the longer term impact. There’s been some research showing that habitual daytime napping (a 2024 meta-analysis of 44 studies showed higher risks for cardiovascular/metabolic disease and all cause mortality). However these are all observational, and it could well be that if you’re napping everyday then you might also have poor sleep / underlying health issues to begin with anyway.

I don’t see this as a reason not to take an occasional power nap during the afternoon – I know from experience it can help! But if you feel like you need a nap most days, it might be worth looking into why 🤔

Nap? When? 😴

Women have healthier immune systems – they respond better to infection1 – but also get most auto-immune diseases far more often. This could be due to sex differences in hormone concentrations or because of the X chromosomes, which are loaded with important immune-regulating genes such as TLR7 and FOXP3. Women only receive one copy of each X-chromosome from their parents, but one of them becomes inactivated at random2. However, a surprising percentage (around 25%) of all genes on the X escape this inactivation process. Thus, women actually receive an increased ‘dose’ for these particular genes compared to males.

Now, researchers have found further evidence to support the idea that the extra X plays a role in making female mice susceptible to developing lupus. They discovered that male patients suffering from Klinefelter’s syndrome (XXY), were equally likely to suffer from lupus as females3 – showing that there was clearly some involvement from the additional X beyond hormones.

Most studies that examine immune responses don’t separate these groups for analysis. So this field has much more research to do before we can really understand the role of sex differences in immunity (and how much of that is due to genetics vs. hormones).

Should sex-specific vaccines or autoimmune therapies be considered the standard of care?