Brief Summary
Dr. Elizabeth Klerman discusses the vital functions of sleep, including healing, detoxification, memory consolidation, and immune system function. She addresses the optimal amount of sleep needed, the impact of sleep phases, and the effects of being a night owl versus an early bird. The discussion covers the cognitive, physical, and emotional effects of sleep deprivation, the long-term impacts of sleep disorders, and strategies for improving sleep. Dr. Klerman also touches on the role of technology in tracking sleep and the importance of mentoring the next generation of sleep scientists.
- Sleep is essential for various bodily functions, and insufficient sleep can lead to metabolic changes, mood alterations, and other physiological issues.
- The optimal amount of sleep varies among individuals and age groups, with most adults needing around eight hours.
- Sleep disorders can have significant long-term health impacts and should be addressed by a sleep physician or psychologist.
- Strategies for improving sleep include maintaining a regular sleep schedule, creating a dark and cool sleep environment, and avoiding caffeine and alcohol before bed.
Introduction
Jen Flynn introduces Dr. Elizabeth Klerman, a Professor of Neurology at Massachusetts General Brigham Hospital and a Scholar in Medicine Fellow at Harvard Medical School. Dr. Klerman's research focuses on circadian and sleep research principles, mathematical analysis, and modelling of human circadian sleep, neurobehavioral mood, and performance rhythms. She has received the Sleep Research Society Distinguished Scientist Award in 2024 and mentors students and junior faculty locally and internationally.
The Primary Purpose of Sleep
Dr. Klerman explains that the primary purpose of sleep is not fully understood, but it enables the body to prepare to be awake. Sleep allows for recovery and the proper functioning of various bodily processes, such as metabolism, mood regulation, and other physiological functions. Every animal sleeps or has a sleep-like behaviour, suggesting an evolutionary advantage. Sleep may have co-evolved with the immobilisation of humans and other daytime-active creatures at night, allowing for the recovery of physiological functions.
Optimal Amount of Sleep
The optimal amount of sleep may vary for different functions, such as metabolism and immune function. The amount of sleep a person gets is influenced by the circadian factor, which promotes wakefulness or sleep at certain times of day, and the homeostatic factor, which is determined by how long a person has been awake. Most people are limited by the amount of time they allow themselves to sleep. Waking up without an alarm clock is a good indicator of getting enough sleep. The average sleep duration is around eight hours, but individual needs vary across age groups, with children and adolescents needing more sleep.
Sleep Phases
Sleep consists of two major stages: rapid eye movement (REM) sleep, during which most dreams occur, and non-REM sleep, which has stages 1, 2, and 3 corresponding to the depth of sleep. Different things happen in different stages of sleep, and it is not possible to selectively choose one stage over another. Waking up frequently during the night does not necessarily mean getting more of one stage than another.
Night Owl vs Early Bird
Being a night owl or an early bird affects sleep, as some people are biologically predisposed to be early risers or late sleepers. This tendency changes across ages, with younger people tending to be earlier and adolescents getting later. The conflict between people's biological tendencies and societal demands can lead to health issues, such as social jet lag, which occurs when people have different sleep schedules on weekdays and free days. Daylight Saving Time can also disrupt body clocks, leading to adverse physiological effects.
Daylight Saving Time
Making Daylight Saving Time permanent would likely result in more adverse health outcomes. The United States has tried permanent Daylight Saving Time twice before, but it ended due to unpopularity. Permanent Daylight Saving Time can lead to less sleep at night, increased traffic accidents, and children going to school in the dark. It disproportionately affects people of lower socioeconomic status who have to wake up early for work.
Effects of Sleep Deprivation
Sleep deprivation has cognitive, physical, emotional, and economic effects. It can lead to prediabetes, weakened immune function, mood changes, car accidents, medical errors, and impaired decision-making. Insufficient sleep is associated with changes in psychiatric disorders, such as depression, and can increase blood pressure.
Long Term Impacts of Sleep Disorders
Sleep disorders, such as sleep apnea, restless legs syndrome, REM behaviour disorder, and sleepwalking, have different long-term health impacts. Obstructive sleep apnea is associated with cardiovascular and cognitive problems. Restless legs syndrome may be caused by abnormalities in the bloodstream. People with REM behaviour disorder are more likely to develop certain neurological diseases. Sleepwalking is usually outgrown in a safe environment. Sleep medicine is a field with diagnoses and treatments, and people should seek help if they experience tiredness after being in bed for eight hours or if their bed partner complains about their sleep habits.
Insomnia
Insomnia can be caused by various factors, including circadian influences and societal demands. The best way to synchronise the body clock is by having light, especially in the morning. There are different types of insomnia, such as difficulty falling asleep, difficulty staying asleep, and waking up too early. Cognitive behavioural therapy for insomnia is recommended over long-term medication use, especially for older people.
Outside Factors Influencing Sleep
Outside factors, such as small children, shift work, menopause, noisy neighbourhoods, and light pollution, can influence sleep. While it is unknown if the long-term effects of insufficient sleep can be reversed, it is important to try to sleep more. Control what you can control, such as giving yourself enough time to sleep, avoiding horror movies and caffeine before bed, and creating a relaxing bedtime routine. Advocate for societal changes, such as later school start times and better support for families.
Advocacy for Societal Change
Advocacy can help reframe sleep as a long-term investment in health and align it with policy-making about health interventions, school start times, and Daylight Saving Time. Successful public health campaigns, such as Mothers Against Drunk Driving, seatbelts, and anti-cigarette smoking, can serve as models for advocating for better sleep policies.
Alertness vs Tiredness
The brain is not good at self-assessment, and people may not accurately perceive their level of tiredness or alertness. People's self-assessment depends on their comparison to how sleepy they felt before. It is important to be aware that you may not be aware you're asleep until you've woken up.
Technologies for Sleep
The effectiveness of apps, wearables, and other technologies for tracking sleep depends on the specific device and software version. These devices measure downstream physiology, such as breathing and movements, but not brainwaves, which is where sleep happens. If a wearable helps you get more sleep, it can be beneficial.
Mentoring the Next Generation of Scientists
Mentoring is essential for teaching patient-oriented research, which requires one-on-one interaction to refine ideas and communicate them effectively. The current funding situation poses a challenge, as less funding for junior investigators may lead to them leaving the field. Supporting senior faculty who support junior faculty is also important.
Advice for Improving Sleep
If you want a nap and you can nap in a safe place, you should nap. There's no evidence that people can sleep when they're not tired. Give yourself extra time for sleeping and maintain a somewhat regular schedule. Avoid caffeine and alcohol, and create a dark, cool sleep environment. There are no shortcuts to good sleep, and behaviour change is hard. If you take a nap, limit it to 45 minutes to avoid sleep inertia. Prioritise sleep over other activities and count all sleep, including falling asleep on the sofa, into the total amount of sleep you're getting over 24 hours.
