Biological Rhythms: Implications for Clinical Practice (01:38)
Barb Bancroft introduces her lecture and defines chronobiology and circadian rhythms as they relate to physiology over a 24 hour period.
Exogenous Clues to Maintain Daily Rhythms (02:27)
Bancroft discusses how dawn and dusk, alarm clocks, and daily routines indicate circadian rhythms. Most people would sleep for eight hours and twenty minutes in a dark, quiet room. Disturbances change the brain to an awake mode.
Circadian Rhythm and the Brain (01:41)
The suprachiasmatic nucleus (SCN) is located in the hypothalamus above the optic chiasm. It coordinates all hypothalamus activities, including the sleep/wake cycle, appetite and satiety, bowel movements, smell, taste, thirst, temperature, sexual function, hormonal production, emotions and blood pressure.
How does the Central Biological Clock Work? (03:10)
Light hitting the retina and retinal ganglion cells sends a message to the SCN to regulate melatonin production. Blue light in mobile devices suppresses melatonin and can disrupt sleeping patterns.
Chronobiology Genes (04:57)
The Clock, Per, and Tim genes regulate circadian rhythms. Bancroft explains the Clock gene's dysfunction in bipolar disease. Lithium re-sets the central biological clock and stops the manic phase. Patients on Lithium need annual TSH monitoring; constipation can indicate thyroid disease.
Individualized Sleep/Wake Cycles (04:02)
Ten percent are "owls" and ten percent are "larks;" the rest are "hummingbirds." A lark, Bancroft had trouble working nursing night shifts. The internal clock runs faster in elderly people, who go to bed around 7 p.m. and wake up at 2 a.m.
Peripheral Circadian Clocks (04:32)
Clocks in organ tissues synchronize with the central clock. The liver controls glucose and produces cholesterol and clotting factors during sleep. The gastrointestinal tract slows; nocturnal diarrhea may be caused by Metformin or diabetes. The pancreas times insulin with glucose production.
Shifting Peripheral Clocks (03:41)
Changing meal times uncouples peripheral clocks from the central clock by twelve hours. Going back and forth between night and day shifts causes weight gain and increases risk of type II diabetes and cardiovascular disease. Breakfast should be the biggest meal.
Early Birds Eat More Worms (02:19)
People with healthy circadian clocks eating earlier in the day lose more weight. Weight loss ability depends in part on the clock gene. The kidney regulates blood pressure and adipose tissue regulates fat cells.
Interest in Biological Rhythms (03:18)
Shift work and air travel led to chronobiology research during the 20th century. Bancroft relates a story about pilots who fell asleep flying from Australia to Los Angles; the industry now requires two sets of crew for long haul flights.
Jet Lag (02:33)
Flying east shortens the day and flying west lengthens the day; it is easier to synchronize the body clock flying west. View a list of jet lag symptoms and hear travel advice for adjusting to a new time zone.
Cancer and Jet Lag (03:25)
Cholangiocarcinoma of the liver has been linked to traveling across time zones for many years. Bancroft shares her story of being diagnosed with the disease; she travels frequently for work.
"Social" Jet Lag and Daylight Savings (02:08)
We are likely to experience symptoms similar to jet lag when sleeping in on the weekends. This triples the odds of being overweight. There are 10% more traffic accidents in the first weeks after the spring time change.
Shift Work (06:13)
Seven million Americans work nontraditional hours. Incremental cost for productivity loss, absenteeism, turnover, work-place accidents and increased insurance and medical costs is over $10,000 per shift worker annually. Sleep apnea, mental health disorders, heart disease, and obesity are common. Hear accident and cancer statistics.
Managing Shift Work Symptoms (03:32)
Workers rotating between day and night shifts are at risk for sleep and mood disorders due to low serotonin. Over the counter melatonin doses are too high; only 0.3 to 1 mg is needed. Modafinil (Provigil) and Armodafinil (Nuvigil) boost alertness.
Shift Work and Hospital Errors (02:19)
Most errors are made between 4 and 6 a.m. Bancroft shares a story of her friend Patti, a night owl, having trouble focusing during a day shift. Driving between 4 and 6 a.m. increases accident risk sixteen times.
Hair Samples and Circadian Rhythms (01:10)
Yamaguchi University researchers analyzed shift worker circadian rhythms. Their sleep pattern shifted by seven hours each week, but their body clock only shifted by two hours. Shift workers should negotiate higher salaries.
24 Hour Clock and Body Changes: ADH (04:52)
ADH peaks at midnight and concentrates urine. Most people urinate once or twice nightly; menopause and aging can cause nocturia. Hear monitoring requirements and contraindications for desmopressin acetate (Noctiva).
Notes on the "Old" Kidney (03:00)
AHD may be involved in memories formed during sleep; poor sleep and alcohol consumption can contribute to dementia. Chronic renal insufficiency can lead to nocturia. Desmopressin (DDAVP) can treat child enuresis and improve grades.
Other Influences on ADH (01:57)
Alcohol inhibits anti-diuretic hormone while narcotics boost it.
Oxytocin peaks from midnight to 1 a.m., increasing desire for sex, intimacy and bonding. Pets also increase oxytocin. It triggers uterine contractions; pregnant women are most likely to go into labor at night. Hear birth time statistics and learn about vaginal seeding.
Glymphatic System (01:58)
The brain's lymphatic system only opens during sleep, cleansing it of oxidants and inflammatory mediators. Poor sleep accumulates toxins, leading to memory disorders over time. Naps also open the glymphatic system.
Growth Hormone (04:08)
GH levels are highest at 2 a.m.; we only grow during sleep. Babies and children experience growing pains at night; teenagers can grow up to half an inch in one night. Growth is saltatory, not linear.
Tonsils, Sleep Apnea, and "Behavioral" Problems (03:59)
Adenoiditis, ADHD and big tonsils cause sleep disturbances and disrupt child growth. Tired children often become inattentive and fidgety, and are misdiagnosed as hyperactive or having behavioral problems. Bancroft discusses indications for tonsillectomies and adenoidectomies.
Chronic Lack of Sleep in Children (02:19)
Children with chronic sleep apnea have an increased obesity and depression risk; symptoms can mimic ADHD. Hear sleep requirements for different age groups. Some schools are starting later, according to teenage circadian rhythms.
Melatonin peaks at 2 a.m. Blue and LED light sources and alcohol decrease melatonin. Melatonin also boosts the immune system, decreases circulating sex hormones, and decreases endocrine related cancers.
Melatonin and Breast Cancer (06:43)
Light at night increases breast cancer risk; blind women have unusually low rates. Age and obesity decrease melatonin production; most people who live to 100 have breast or prostate cancer. The relative risk for taking post-menopausal hormones is 1.26.
Nutrition and Breast Cancer Risk (01:47)
Bancroft mentions a new study showing that girls who eat abundant fruit during adolescence have a 25% decrease in breast cancer risk. Another study found that women with increased alcohol consumption had a higher breast cancer risk and lower heart disease risk.
Sleep, Glorious Sleep (01:45)
Humans will die from ten days of sleep deprivation. Sleep increases melatonin secretion, serotonin and norepinephrine, and memory while decreasing cortisol and the type 2 diabetes risk. Poor sleep alters genes involved in inflammation, immunity, and stress coping abilities.
Sleep Cycles (04:15)
Experts recommend sleeping on a big decision to consolidate information. After three or four slow-wave cycles, we enter REM sleep, during which the brain is awake and major muscles are atonic. Learn about other physiological activities during REM sleep.
REM Sleep and Erections (03:14)
Men get multiple erections during REM sleep. Bancroft explains the stamp test as it relates to psychologically caused erectile dysfunction.
Learn about an autoimmune disease affecting the brain's inability to regulate the sleep-wake cycles, causing patients to enter REM sleep within minutes.
REM Sleep and Menopause (02:38)
Hot flashes occur during REM sleep. Estrogen, clonazepam or Neurontin can help control symptoms. Bancroft describes a study in which husbands experienced simulated hot flashes in a sleep lab.
Sleep Changes and Disturbances (02:56)
ICU psychosis can occur due to 24 hour ward lighting; nurses should provide clues to the time of day and week day. Hypersomnia and insomnia can signal depression; light therapy can treat both depression and sleep disorders.
Sleep Disorders and Diseases (03:02)
Cluster headaches wake patients at a regular intervals and are treated with oxygen. Most people who violently act out dreams during REM sleep develop Parkinson's disease or dementia after a decade.
1 a.m. to 4 a.m. (01:47)
Normal skin cells divide between 1 and 4 a.m. Decreased saliva production causes a buildup of mouth bacteria overnight, causing halitosis.
3 a.m. to 6 a.m. (06:12)
The pain threshold decreases between 3 and 6 a.m.; nurses can encourage pre-emptive analgesia. Inflammatory mediators and menstrual cramps increase. Tooth aches and post-operative pain increase at 4 a.m. Bancroft discusses issues with giving pain medication PRN; patient-controlled analgesia works better.
4 a.m. Pulmonary Function (02:37)
Bronchoconstriction peaks at 4 a.m. COPD patients have increased difficulty breathing and asthma attacks are most likely to occur. Pulmonary function is best between 3 p.m. and 5 p.m.; parents should wake asthmatic children at 2 a.m. for monitoring.
Bronchoconstriction at Night (02:43)
The vagus nerve input to the bronchioles causes bronchoconstriction peaking at 4 a.m.; asthmatics bronchoconstrict more than 58%. Hear how GERD can also trigger bronchoconstriction, treatable with Nexium.
Blood Sugar (04:53)
Blood sugars are lowest around 3-4 a.m. Hypoglycemia can cause seizures and nightmares. NPH should be given at 10 p.m. to coincide with the early morning sugar rise. Longer acting insulins like glargine (Lantus) or detemir (Levemir) avoid this risk.
4 a.m. to 6 a.m. (01:22)
Body temperature and blood pressure are lowest between 4 and 6 a.m. Melatonin secretion falls; adrenalin and cortisol begin rising. There is usually a final REM sleep before 6 a.m. The snooze alarm disrupts the biological clock.
6 a.m. Wake Up (03:19)
Most people rely on alarms to wake up and do not know what time they naturally rise. Using the snooze button re-sets the body clock and makes it harder to function.
6 a.m. Hormones (03:09)
Increased prostaglandin production begins menstruation. Bancroft explains menstrual synchrony. Blood insulin levels are lowest as glucose rises for getting out of bed, known as the "dawn phenomenon" in diabetics.
6 a.m. to 8 a.m. Blood Sugar (02:55)
The liver works overnight to keep blood sugars within a normal range. Give Metformin (Glucophage ER, Fortamet, Glumetza) at bedtime if it is given once a day. Long-acting Metformin can alleviate gas and diarrhea side effects.
Metformin Indications (02:51)
The insulin drug causes weight loss. It also prevents weight gain and diabetes secondary to atypical anti-psychotic use, particularly clozaril and olanzapine. Women with lupus taking prednisone or polycystic ovary syndrome patients can also benefit from reducing insulin resistance.
6 a.m. to 8 a.m. Clotting Factors (02:16)
The liver produces clotting factors II, VII, IX and X overnight, increasing morning clotting factors. Warfarin (Coumadin) should be taken from 8-10 p.m. Drugs given once daily work best in the first 12 hours. Bancroft discusses direct oral anticoagulants.
6 a.m. to 8 a.m. Cholesterol (02:01)
The liver produces LDL cholesterol at night via the HMG-CoA reductase enzyme; statin drugs inhibit this enzyme. Most statins work best given before bed except Crestor and Lipitor. Simvastatin (Zocor) interacts with other drugs.
6 a.m. to 7 a.m. Blood Pressure (00:54)
Blood pressure and heart rate rise due to adrenalin and cortisol; vessel constriction increases stroke and myocardial infarction risk. Most people wake up at 7 a.m.
7 a.m. Sex Life (04:32)
Testosterone levels are highest at 7 a.m.; 38% of men prefer sex in the morning. Exercise and coffee lower erectile dysfunction risk. Bancroft shares a study of rats showing sex boosts neurogenesis and tells the story behind the Coolidge Effect.
7 a.m. Testosterone (02:06)
Testosterone levels are highest in men under 45; the time of day matters less for men over 45. Obesity lowers testosterone and delays puberty in boys.
Time to Exercise (02:39)
The best time to exercise is 7:45 a.m. If exercising at night, allow several hours to avoid sleep disruption. Morning exercise benefits include reduced hunger throughout the day, increased insulin sensitivity, boosted serotonin and norepinephrine, and building new neurons.
8 a.m. to 10 a.m. Cardiac Health (09:06)
Heart disease patients have increased risk of angina, cardiac arrhythmias, sudden cardiac death, and death associated with congestive heart failure. Patients should chew aspirin upon waking for rapid results. Bancroft discusses dosage, coated aspirin usage, and the link between dementia and inflammation.
Acute Coronary Syndrome in the Morning (02:11)
Morning heart attacks cause more myocardial damage due to lower levels of salvage kinases. Despite a preference for morning sex, less than 1% of heart attacks occur during sex. Most cases of sudden death during sex occur in extramarital affairs.
Morning Smoking (02:20)
Cigarettes between 6 and 8 a.m. can contribute to myocardial infarction risk due to vasoconstriction and increased blood pressure and heart rate. Bancroft discusses addiction risk among teenagers.
7:30 a.m. Embolism Risk (02:10)
It takes about 30 minutes for a deep vein thrombosis to break off and flow to the lungs; symptoms resemble those of heart attacks. DVTs can form overnight; nurses should get post-operative patients moving as soon as possible.
7-7:30 a.m. Stroke in Progress (04:20)
Patients can wake up with a stroke; hear neurological damage statistics per minute of brain attack. Bancroft explains how Solitaire machines extract clots. Asking when the patient last was seen as "normal" can help determine the tPA window.
7 a.m. to 8 a.m. Rheumatoid Arthritis (06:07)
Patients should take NSAIDS or Aleve when they wake; ibuprofen should be spaced two hours after aspirin. Bancroft discusses how Remicade, Humira and Cimzia have improved patient mobility. Vascular inflammation increases heart attack risk in young women.
Aspirin's Role in Inflammation (04:25)
Aspirin prevents heart disease and colon polyps and reduces colon cancer risk. Morning is best for colonoscopies due to increased doctor alertness. Aspirin is no longer recommended for pain management or temperature elevation; it is prescribed for Kawasaki disease and juvenile rheumatoid arthritis.
Inflammatory Pain or Fever (02:49)
Acetaminophen only works in the hypothalamus to reduce central pain and temperature. Ibuprofen works both centrally and on peripheral prostaglandins. Bancroft discusses the limitations of Tylenol, supported by a 2016 meta-analysis.
7 a.m. Histamine Release (01:37)
Hay fever and allergic rhinitis patients suffer most in the morning. Researchers have identified a circadian clock in the nose.
7:30 a.m. Medications (05:44)
Proton pump inhibitors should be taken 30 minutes before breakfast to stop acid production; view a PPI list. Thyroid hormone and insulin should also be taken before breakfast. Rapid-acting insulin can be taken with breakfast. Calcium supplements do not increase heart disease risk.
7 a.m. to 8 a.m. Break the Fast (03:39)
Metabolism is high in the morning; breakfast should be the largest meal of the day. Eggs contain choline, vitamin D, and lutein, and do not raise cholesterol. Up to 14 eggs per week are recommended, but diabetics are restricted to three eggs.
8:30 a.m. Bowel Movement (04:17)
Coffee, cigarettes, or eating breakfast can trigger a bowel movement. Morning colonoscopies are recommended for doctor alertness. Patients surveyed sleeping less than six hours per night were 50% more likely to have colon polyps, due to inflammation.
10 a.m. to 12 noon (02:02)
The complexion looks best at 10 a.m. Larks are most alert between 10 a.m. and 12 p.m.; owls are still grouchy. People are genetically predisposed to be larks, owls, or hummingbirds. Death is common around 11 a.m. for older patients.
12 p.m. Lunch (02:56)
Lunch should be substantial and eaten away from the desk. From 1 to 2 p.m., blood glucose dips; physical activity is beneficial. Napping can reverse the hormonal impact of a poor night's sleep and restore biomarkers of neuroendocrine and immune health to normal levels.
2 p.m. (02:40)
The sense of smell peaks at 2 p.m.—not an ideal time for nurses to change wounds. Bigger nostrils also increase the sense of smell. TSH levels are lowest, giving the impression of disease fluctuation among mild hypothyroidism patients.
3 p.m. to 5 p.m. (03:01)
Fastest reaction times occur at 3:30 p.m. Pulmonary function is optimal; the sympathetic nervous system keeps bronchioles dilated. Snacking at 4 p.m. regulates blood glucose levels and increases alertness; protein is recommended. Owls function well between 4 p.m. and 5 p.m.
7 p.m. Dinner (02:34)
Body temperature peaks at 7 p.m. and heart rate and blood pressure peak between 5 and 6:30 p.m. Meals should be small and at least three hours before bedtime. High-fat meals decrease Viagra effectiveness, but not Vardenafil (Levitra) or tadalafil (Cialis).
9 p.m. to 11 p.m. (01:49)
Mealtimes and lighting during sleep are pivotal in weight management. GERD symptoms are worst between 9-11 p.m.; esophageal sphincter triggers vary.
Overnight Acid (05:09)
The parasympathetic system produces gastric acid; it is best to take H2 blockers (Tagamet, Axid, Zantac or Pepcid) before bedtime. Learn about Tagamet's life threatening drug interactions. OTC drugs are given at half-dosage; patients should double their dose.
9 p.m. Dim-light Melatonin Starts (02:32)
Lowering the room temperature and taking a hot shower helps people to sleep longer. Osteoarthritis pain is worse at 9 p.m.; patients taking NSAIDs with GI stress should take Pepcid. Diclofenac (Voltaren) cream helps small body areas.
10:30 p.m. (04:12)
Bowel movements are suppressed overnight in healthy people; nocturnal diarrhea can signal diabetes. Sleep patterns are genetic and consist of larks, owls, or hummingbirds. Bancroft compares lark and owl body clock schedules. Owls tolerate rotating shifts better than larks.
10 p.m. to 12 a.m. (02:16)
Owls are most alert in the late evening while larks are sleeping. Studying the night before an exam and getting quality sleep is most effective.
Nighttime and Blood Pressure (02:44)
Blood pressure should drop from 10% to 20% during sleep. "Non-dippers" are at higher risk for heart disease, stroke and renal failure; African-Americans tend to be "non-dippers." Blood pressure medications can be given at night or split into two doses.
Nighttime Restless Legs Syndrome (03:22)
RLS occurs when melatonin inhibits central dopamine secretion; it can be caused by iron deficiency. Treatments include iron, levodopa, dopamine agonists, gabapentin, valproic acid, and clonidine. Boosting dopamine can lead to addiction. Low dopamine from SSRIs can cause teeth grinding.
10 p.m. to 10:30 p.m. Bedtime (02:15)
Social media and screen time should cease two hours before bedtime; LED and blue lights interrupt sleeping patterns by preventing melatonin rise. Orange light is conducive to sleeping.
11 p.m. to 1 a.m. (01:03)
Nocturnal nose-picking and nosebleeds occur 90 minutes into sleep. Most sexual activity occurs between 11 p.m. and 1 a.m.
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