By Dr. Chin Moi Chow, The University of Sydney
Sleep is vital for overall health. Poor sleep can cause daytime sleepiness, fatigue, and mood deterioration and has implications for poor health outcomes. Getting six or fewer hours each night may also provoke increased appetite leading to risk of weight gain and, in the longer term, the risk of developing diabetes and cardiovascular conditions. There is also a significant association between poor sleep and depression.
For older adults (those over 65) the quest for a good night’s sleep can be particularly challenging. Research has discovered that even those older adults who are healthy may display significantly disturbed sleep with longer sleep onset time, and frequent awakenings during the sleep period, with complaints of symptoms of insomnia.
Causes of sleep disturbance
Sleep deficiencies may be linked to inadequate zeitgebers, the environmental cues which impact on the timing of sleep and waking. The most important zeitgeber that entrains sleep-wake timing is natural light exposure. Individuals who are house bound or institutionalised, with diminished time cues for meals, activities or social cues may experience poor sleep.
Sleep disturbance may also be due to life stressors, muscular pain, and the use of medications, or the sleep environment being too hot or cold, noisy or light. Visual and light stimulation, associated with television viewing or computer use prior to bedtime, may delay sleep onset and disrupt sleep. Daytime napping to top up nocturnal sleep is common in older adults and may cause awakenings during the night and/or early waking.
Community-dwelling healthy individuals have better sleep than healthy individuals living in nursing homes. This could be caused by building design that does not adequately deliver abundance of natural light into the living and dining rooms. Organisational structure and culture of nursing homes also may not provide sufficient opportunities for light exposure (such as organised outdoor activities), or for exercise. Diminished light exposure and limited programmed physical activities may result in individuals sleeping at all times of the day and night, overall resulting in poor sleep.
Although sedative-hypnotics may be effective in promoting sleep onset and sleep duration, these medications can impair balance and therefore increase the risk of falls, fall-related injuries and hip fractures in older adults.
Natural approaches to healthy sleep may have specific relevance for older adults. These include exposure to natural light, exercise and diet.
Natural light exposure
Natural light exposure has the benefit of synchronising the sleep-wake rhythm, since light suppresses the production of melatonin, a hormone that induces sleep. Thus sufficient light exposure during the day (for example, mornings and evenings) increases alertness. The onset of darkness signals the release of melatonin and sleepiness. Its peak production during the night helps consolidate sleep.
Exercise and diet
Exercise and diet may positively influence and modify sleep, and are vital for sleep health and healthy ageing. Exercise and diet are two approaches that can be harnessed and incorporated into daily living to improve sleep, without the side effects of hypnotic drugs.
Subjective reports of sleep suggest that moderate aerobic exercise is effective in promoting sleep in older adults. A well-validated questionnaire, the Pittsburgh Sleep Quality Index (PSQI), has been employed in many of the aerobic training studies. The training period ranged from 16 weeks to 12 months, the frequency of training being 3x per week. The PSQI showed a consistent self-reported sleep improvement during the past month.
The effects of aerobic exercise training have also been investigated through objective sleep measures in older adults, using polysomnography (the gold standard measure of sleep quality and quantity). This study demonstrated a significant reduction in light sleep (non-rapid eye movement (NREM) sleep stage 1), an increase in NREM sleep stage 2, and a decrease in the number of awakenings. An increased stage 2 sleep may have some physiological significance, since its associated sleep spindle appearance may protect individuals from being woken, consistent with reduced wake time during the sleep period.
Supervised anabolic exercises (resistance or weight training), involving three sessions per week for 10 weeks, showed self-rated sleep improvements using the PSQI. It is noteworthy that both forms of training (moderate intensity aerobic and high intensity anabolic exercise) alleviate depression. Apart from sleep improvements, aerobic exercise training has the added advantage of increasing cardiovascular fitness, and anabolic exercise training increasing muscle mass and bone density and thereby buffering the risk of falls and fall-related injuries.
Before entering into a program of moderate exercise training, it is prudent to evaluate the medical status and level of physical conditioning of the individual. For example, older adults are at greater risk of falls, may suffer from arthritis, and may have pre-existing cardiovascular (hypertension) or metabolic conditions (diabetes). Medical clearance prior to beginning an exercise program is essential. Notably, sedentary adults need to undergo a conditioning period of gradually building up to a physical fitness level to prepare for moderate intensity exercise training.
Pre-sleep food selection
Along with exercise, eating the correct foods before bedtime is an easily adapted pre-sleep behaviour that can enhance sleep. It is well-known that caffeinated beverages can delay sleep onset and adversely affect the depth of sleep in susceptible individuals. Alcohol can also delay rapid eye movement (REM) sleep and cause sleep disruptions.
Some consideration of the foods selected for the evening meal may have a significant impact on the quality of sleep. Research has shown that foods that increase the availability of tryptophan, or those that contain high levels of tryptophan, may be effective in promoting sleep. Foods high in tryptophan can be found in whey proteins (a by-product formed from processing milk into cheese), milk, yoghurt, pumpkin seeds, tart cherry juice, and cherry-enriched diets. When consumed with carbohydrates, these foods help promote sleep.
Ageing does not necessarily have to be associated with a decline into an unhealthy lifestyle with poor sleep. As seen, healthier sleep can be promoted in the over 65s through adequate natural light exposure during the day, regular moderate exercise and appropriate food choices, especially before going to bed.
About Dr Chin Moi Chow
Dr Chow is a lifestyle scientist for sleep, with a research focus on natural approaches (diet, exercise and thermal comfort-related factors) to sleep health.
She also lectures in exercise physiology at The University of Sydney.
Disclaimer: This article has not been subjected to peer review and is presented as the personal views of a qualified expert in the subject in accordance with the general terms and condition of use of the news-medical.net website.