Chapter 35
Lifestyle+ — 26
The master pacemaker clock for our circadian rhythm is in the suprachiasmatic nucleus, a small region within the hypothalamus, entrained by external cues from light. Exquisite molecular circuitry connects it with our muscle, liver, adrenal gland, kidneys, immune system, heart, and pancreas. Exemplifying the pivotal role of the twenty-four-hour sleep-wake cycle, there’s a rare familial condition of short sleep with no adverse consequences due to a mutation in a molecular clock regulator gene. If only we could simulate that clock control, we might be able to promote better quality and efficiency of sleep with less duration (think genome editing someday in the future).
So we’re faced with the challenge of promoting better sleep that is essential for healthy aging, while aging itself is compromising sleep quality. There are some things that help, like maintaining the same sleep pattern every day, including weekends. That includes a regular pattern of exercise and meals, with an adequate separation of multiple hours from bedtime (think early time-restricted eating). A cool and fully dark, quiet bedroom as well as avoidance of the blue light from electronic devices that disrupts circadian rhythm and suppresses melatonin production are simple tips. The benefit or risk of napping during the day has been a source of debate, but a large observational study found that napping one to two times weekly was linked to a significant reduction of cardiovascular events. Most epidemiologic studies that have looked at napping suggest their duration is important, and longer afternoon naps, especially more than one hour, are associated with risk.
In recent years, the popularity of sleep trackers has soared, including wearables such as the Oura ring, smartwatches, and fitness bands, and smartphone app “nearables” that can be on or beside the bed. Most of these devices rely on an accelerometer to detect movement during sleep and try to extrapolate the duration of REM, non-rapid eye movement sleep phases, and total sleep duration. You can easily fake out that metric by reading in bed, which I have personally tested. More sophisticated devices, like Oura, integrate heart rate, movement, body temperature, and blood oxygen levels, which provides better alignment with formal sleep lab measurements, yet with the advantage of being in one’s own bed. The problem is that there are no standards for the algorithms for their sleep scores and a general lack of validation for accuracy of reporting. Ironically, use of the trackers can induce or exacerbate anxiety, which interferes with sleep quality. On the other hand, self-diagnosis for triggers of poor sleep, such as alcohol, late meals, caffeine, or blue light, can be facilitated with their use.
Few rigorously assessed interventions have been shown to improve sleep quality. Professional organizations recommend cognitive behavioral therapy as first-line treatment because of the body of evidence that has borne out its efficacy. That treatment typically requires a trained therapist along with a significant time commitment and expense. However, in-person coaching of relaxation training, avoidance of stimuli, and improvement in sleep hygiene can be simulated with smartphone apps. A randomized trial of digital cognitive behavioral therapy, using a smartphone app, enrolled over seventeen hundred participants with insomnia and showed improvements of insomnia symptoms along with functional health and psychological well-being. This report and others are encouraging nonpharmacologic ways of improving a healthy sleep schedule.