The research shows that individuals taking naps in the afternoon is associated with a significantly enhanced risk of developing diabetes. It concerns fluctuations in the level of sugar in the bloodstream. After eating, blood sugar levels usually rise, which in return causes the body to secrete a hormone called insulin, one of the chief effects of which is to reduce blood glucose levels. However, if for any reason the rise in blood glucose level is substantial, insulin secretion can follow suit, and this can lead to
low blood sugar (hypoglycaemia) some time later. Hypoglycaemia will generally cause physical and mental energies to fall, and may induce sleepiness to the extent that someone actually feels compelled to sleep. One of the other symptoms that this can give rise to is the feeling of peckishness (particularly for something sweet) on awakening. It might be that before individuals develop full-blown diabetes they are prone to fatigue and sleepiness as a result of a pre-diabetic state. The most common time in the day for this effect to occur is the mid-late afternoon (about 3 hours after lunch). For a lot of us, it reflects the body’s reaction to what a lot of us choose to eat a lunch (something cereal-based).
Now, if an individual habitually has this imbalance, the likelihood is that they’re going to be secreting relatively high levels of insulin too. As a result, one or both of two things can happen in time:
- the body may become somewhat ‘numb’ to the effects of insulin
- the pancreas which secretes insulin can exhaust, leading to inadequate amounts of insulin
Either of these states can lead an individual down a path to type 2 diabetes. And these mechanisms may possibly explain why individuals taking afternoon naps are more prone to developing diabetes in time. It has also been suggested that the need to nap during the afternoon is a sign of some form of sleep disturbance that could be increasing diabetes risk. Here again, though, blood glucose imbalance may be playing a part. The reason is that just like blood sugar levels can fall in the mid-late afternoon, they can fall in the middle of the night too (often at 3.00-4.00 am). In response to this, the body is likely to secrete certain hormones that will liberate sugar from stores fuels such as glycogen in the liver. This will certainly get the body out of a hole, but the problem is the hormones that the body secretes in response to low blood sugar, including adrenaline and cortisol: the two major ‘stress hormones’. Their presence in the system will do nothing to promote deep sleep, and may trip individuals into wakefulness. Individuals may find it difficult to drop off again, which could mean that they really don’t get enough sleep. The ‘sleep debt’ so incurred could easily manifest in the form of afternoon fatigue. Cortisol, as it happens, also antagonises the effects of insulin, which is another mechanism by which blood sugar imbalance may increase diabetes risk.