Another important source of delayed input relates to the fourth impact I will soon identify—this is stress-reduction. Exercise tends to lift one’s mood and enables one to reduce tension in their body (especially the body’s musculature). When there is greater relaxation coupled with circadian alertness during the day, then we are more likely to remain relaxed during the evening. In a relaxed state, we can more easily shut off worrisome thoughts—which relates to the third impact I will be identifying.
It all fits together—sleep (and wakefulness) requires systemic attunement of various bodily functions. It might even be that sleep has a greater impact on the physiological benefits of exercise than the other way around. The relationship is bi-directional (as are many of the relationships between various bodily functions). No one thing does the trick regarding either sleep or exercise– that is why I have identified multiple pathways (not only regarding component one).
Several other changes occur when we exercise in the morning that impact less directly on our evening capacity to fall asleep. First, there is a change in metabolism when we exercise that seems to prepare us later for sleep. Second, there is the matter of weight management: we are more likely to find quality sleep when we are trim. In several different ways, excess weight leads to disrupted sleep (for example, greater chance of snoring) and we know that exercise can provide some assistance in our management of weight (though not as much assistance as most of us wish were the case – it is hard to burn off those extra pounds!).
Third, as we all know, exercise contributes to cardiovascular health and a healthy heart certainly doesn’t hurt us when we are trying to fall asleep: high blood pressure, for instance, is associated with our sensitivity to stress (it works both ways: high levels of stress contributes to high blood pressure and the reverse is also the case). Once again, we see the body operating as a complex organic machine with many highly interdependent parts. Midst all of this complexity there is one simple fact: we sleep better when all parts are working effectively.
There is one final point to make about the timing of exercise. Morning exercise is good, as is exercise engaged throughout the day — up until 2-3 hours prior to bedtime. When we are active just before trying to fall asleep then the physiological outcome is not good. We might be tired, but our body is usually not primed for sleep if we were just on a tread mill. Like alcohol, the pre-sleep exercise might help us fall asleep for a brief period of time – but not for a long period of time.
Indirect Mental Impact: Recalibrating our brain
Exercise helps to modify, “lubricate”, facilitate – and even recalibrate—mental functions. There are two important questions to ask about this indirect impact. First, how does exercise help to recalibrate our brain? Second, what difference does this recalibration make regarding our quality of sleep? I will try to answer both of these very challenging questions in an over-simplified manner (I remind all of us that this is not a neurobiological essay and I am definitely not an expert in this scientific domain). We can begin with the role played by exercise in the strengthening of memory. Recent research suggests that there is a boost in the size of the hippocampus when one is consistently engaged in exercise.
