Sleep Disturbances in Older Adults

Sleep disturbances become increasingly common as we age, and a variety of factors play a role in the advanced phase shift most commonly reported by older adults. Older adults experience less stage 3 and stage 4 deep sleep and less REM sleep, all of which are essential for memory consolidation, cognitive functioning, and muscular repair. Irregular sleep can contribute to common diseases of aging (obesity, cardiovascular disease, diabetes, Alzheimer’s), as well as mental health issues (depression, irritability, etc.). Because sleep is so instrumental to health and longevity, it is important to understand the potential causes of sleep disturbances, after ruling out diagnosable conditions such as obstructive sleep apnea syndrome and restless leg syndrome.

Altered Circadian Rhythm

Many older adults have altered circadian rhythms, which is the internal biological clock that controls daily hormonal oscillations, sleep-wake cycles, and regulates many endocrine system interactions. Even the immune system appears to operate on a circadian rhythm, as well as the microbes in our guts.³ Having a disrupted circadian rhythm can cause sleep disruptions, and blue light has been receiving a large amount of press lately due to its ability to greatly impact our circadian rhythm.

Without environmental and biological cues, circadian rhythms work on a 25 or 26-hour cycle. External factors, like short-wavelength blue light, synchronize our circadian rhythms to a 24-hour cycle that matches the average length of a day on Earth; this is called light entrainment. For example, the blue light coming off of our phone and computer screens has been shown to suppress melatonin, making sleep initiation more difficult for those spending the dark hours before bedtime with bright light exposure on their retinal ganglion cells. Blue light glasses and blue light filters on iPhones have become increasingly popular, but it seems older adults’ sleep issues may be a result of not enough short-wavelength light, rather than too much. Adequate blue-light exposure is necessary for proper entrainment of the circadian rhythm.

Aging Eyes

Aging is caused by a variety of biological processes that deteriorate efficient functioning of our bodily systems. All of our tissues and organs are victims of oxidation and aging, including the eyes. As we age, yellow pigmentation accumulates in the lens; this “yellowing of the lens” reduces short wavelength light transmission to our melanopsin-containing retinal ganglion cells, which leads to less stimulation of these retinal ganglion cells.² Studies have found lens yellowing and reduced blue light transmission are significantly associated with sleep disturbances, likely due to light’s ability to entrain the circadian rhythm.¹

Aging Suprachiasmatic Nucleus (SCN)

The retinal ganglion cells synapse in the SCN, transducing their message to this hypothalamic structure. Because no tissue, organ, or cell is unscathed by the cruel hand of aging, there could be a deterioration in any part of this transduction pathway, from the lens to the RGCs to the SCN. Yellowing of the lens reduces blue light transmission, there may be reduced retinal ganglion cells in older adults, and/or the SCN may have a reduced amplitude in its electrical activity (disruption in the neuron electrical firing).

Altered Hormones

When the circadian rhythm is disrupted, not only is the sleep-wake cycle disturbed, but the hormones that influence and are influenced by sleep (i.e. cortisol, melatonin, etc.) are also altered. For example, bright light during the day can stimulate nocturnal melatonin (while bright light in the evening can suppress nocturnal melatonin, due to the nature of the circadian rhythm).⁴

Women & Menopause

Sleep issues are often more prevalent in women than in men, and this is likely due to hormonal changes throughout the female life cycle. Estrogen and progesterone play an incredibly diverse range of roles in the body, including in the brain. For instance, progesterone increases the synthesis of GABA, an inhibitory neurotransmitter that promotes relaxation and sleep. Similarly, estrogen assists in body temperature regulation, helping keep the body cool, which is essential for sleep initiation. It also increases magnesium uptake and utilization. With the onset of menopause, there is a drastic reduction in progesterone and estrogen, resulting in symptoms that include hot flashes, irritability, and sleep disturbances. Up to two-thirds of menopausal women experience sleep issues.⁵

Men & Testosterone

As men age, their production of testosterone decreases. Low testosterone is linked to worsened sleep quality (i.e. increased nocturnal awakenings), and chronically-high cortisol (caused by sympathetic nervous system activation, released by the adrenals, and common in today’s fast-paced, productivity-centric society) might lower testosterone by inhibiting the production of testosterone.⁷ Obstructive sleep apnea is also more common in men than in women.

Solutions

• Increase blue-light exposure. Get outside during the day, especially first thing in the morning, right upon waking. Try to avoid blue light later in the evening, when it is dark outside.

• Talk to your physician about hormonal replacement therapy (HRT). Studies have shown that exogenous administration of estrogen to menopausal women can improve sleep.⁶ Additionally, the loss of estrogen accelerates aging by reducing antioxidant proteins; this, inevitably, increases aging of the brain (i.e the SCN). BHRT may slow the rate of aging.

• Start an anti-aging, longevity protocol to slow, or even reverse, biological aging. Consider supplements like glutathione, NAD+, vitamin B12, resveratrol, etc.

• Exercise to help keep cortisol levels regulated (another hormone on a circadian rhythm that can also inhibit testosterone production).

• Consider a magnesium supplement, especially if you are a women experiencing menopausal symptoms.

• Talk to your physician about low dose naltrexone to regulate cortisol levels, eliminate cortisol surges near bedtime, and to reduce inflammation that contributes to irritability, anxiety, aging, and thus, sleep issues.

References

1. Kessel L, Siganos G, Jørgensen T, Larsen M. Sleep disturbances are related to decreased transmission of blue light to the retina caused by lens yellowing. Sleep [Internet]. 2011 [cited 2023 Jun 7];34(9):1215–9. Available from: http://dx.doi.org/10.5665/SLEEP.1242  

2. Duffy JF, Zitting K-M, Chinoy ED. Aging and circadian rhythms. Sleep Med Clin [Internet]. 2015 [cited 2023 Jun 7];10(4):423–34. Available from: http://dx.doi.org/10.1016/j.jsmc.2015.08.002  

3. Mazzoccoli G, Vendemiale G, La Viola M, De Cata A, Carughi S, Greco A, et al. Circadian variations of cortisol, melatonin and lymphocyte subpopulations in geriatric age. Int J Immunopathol Pharmacol [Internet]. 2010;23(1):289–96. Available from: http://dx.doi.org/10.1177/039463201002300127  

4. K. Mishima, M. Okawa, T. Shimizu, Y. Hishikawa. Diminished Melatonin Secretion in the Elderly Caused by Insufficient Environmental Illumination. The Journal of Clinical Endocrinology & Met [Internet]. 2001 Jan 1 [cited 2023 Jun 7];86(1). Available from: https://academic.oup.com/jcem/article/86/1/129/2841127  

5. Women’s health concern. Menopause and insomnia [Internet]. Womens-health-concern.org. [cited 2023 Jun 7]. Available from: https://www.womens-health-concern.org/wp-content/uploads/2022/12/17-WHC-FACTSHEET-Menopause-and-insomnia-NOV2022-B.pdf  

6. Polo-Kantola P, Erkkola R, Helenius H, Irjala K, Polo O. When does estrogen replacement therapy improve sleep quality? Am J Obstet Gynecol [Internet]. 1998 [cited 2023 Jun 7];178(5):1002–9. Available from: https://pubmed.ncbi.nlm.nih.gov/9609575/  

7. Barrett-Connor E, Dam T-T, Stone K, Harrison SL, Redline S, Orwoll E, et al. The association of testosterone levels with overall sleep quality, sleep architecture, and sleep-disordered breathing. J Clin Endocrinol Metab [Internet]. 2008 [cited 2023 Jun 7];93(7):2602–9. Available from: http://dx.doi.org/10.1210/jc.2007-2622