ABSTRACT
The aim of this study was to evaluate the effects of a 200-mg administration of caffeine on polysomnographic sleep variables and quantitative sleep electroencephalography (EEG) in 12 young (20-30 years) and 12 middle-aged (40-60 years) moderate caffeine consumers (one to three cups of coffee per day). All subjects were submitted to both a caffeine (200 mg) and placebo (lactose) condition in a double-blind cross-over design. The conditions were separated by 1 week. Compared with the placebo condition, the evening ingestion of caffeine lengthened sleep latency, reduced sleep efficiency, and decreased sleep duration and amount of stage 2 sleep in both age groups. Caffeine also reduced spectral power in delta frequencies in frontal, central and parietal brain areas, but not in prefrontal (PF) and occipital regions. Moreover, caffeine increased spectral power in beta frequencies in frontal and central brain areas in both age groups. A suppression of spectral power in the PF area in low delta frequencies (0.5-1.00 Hz) and a rise in spectral power in the parietal region in high alpha (10.00-12.00 Hz) and beta frequencies (17.00-21.00, 23.00-25.00, 27.00-29.00 Hz) occurred solely in middle-aged subjects. No such changes were noticeable in young subjects. Generally, caffeine produced similar effects in young and middle-aged subjects. Only a few frequency bins showed more effects of caffeine in middle-aged subjects compared with young subjects. Furthermore, sleep EEG results do not entirely support the hypothesis that caffeine fully mimics the effects of a reduction of homeostatic sleep propensity when following a normal sleep-wake cycle.
Subject(s)
Aging/physiology , Caffeine/pharmacology , Caffeine/therapeutic use , Circadian Rhythm , Habits , Sleep Wake Disorders/epidemiology , Sleep/drug effects , Adult , Aged , Beverages , Caffeine/administration & dosage , Coffee , Cross-Over Studies , Double-Blind Method , Drug Administration Schedule , Electroencephalography/drug effects , Female , Frontal Lobe/drug effects , Humans , Male , Middle Aged , Parietal Lobe/drug effects , Prefrontal Cortex/drug effects , Sleep Stages/drug effectsABSTRACT
Recent reports have called into question the relevance of periodic leg movements during sleep disorder (PLMSD) as a specific clinical entity. Because periodic leg movement in sleep index (PLMSI) increases with age, it has become an important exclusion criterion in research on aging. However, it is unknown if PLMSI is related to sleep quality in middle-aged subjects without sleep complaints. The sleep of 70 healthy, middle-aged subjects (age 40 to 60 years) without sleep complaints was evaluated. Subjects were divided into two groups according to their PLMSI severity: (1) 43 subjects (28 women, 15 men) were in the low PLMSI group (<5) and (2) 22 subjects (9 women, 13 men) were in the high PLMSI group (>10). A significantly higher proportion of men than women showed PLMSI greater than 5. There was no significant effect of PLMSI severity group for polysomnographic sleep parameters. PLMSI exerted a small but significant effect on subjective sleep quality, especially in middle-aged men. These results raise questions about the relevance of PLMSI as a pathological index for middle-aged subjects without sleep complaints and support the notion that an increase in PLMSI may be part of the normal process of aging associated with the loss of dopaminergic function.
Subject(s)
Nocturnal Myoclonus Syndrome/physiopathology , Nocturnal Myoclonus Syndrome/psychology , Adult , Circadian Rhythm/physiology , Electroencephalography , Electromyography , Electrooculography , Facial Muscles/physiopathology , Female , Humans , Male , Mass Screening/methods , Middle Aged , Muscle, Skeletal/physiopathology , Nocturnal Myoclonus Syndrome/diagnosis , Polysomnography , Severity of Illness Index , Sleep Stages/physiology , Surveys and QuestionnairesABSTRACT
STUDY OBJECTIVES: To evaluate the effects of a 25-hour sleep-deprivation episode on quantitative waking electroencephalogram (EEG) and subjective alertness in young and middle-aged subjects. DESIGN: A 25-hour constant-routine protocol followed by a daytime recuperative sleep episode. SETTING: Chronobiology laboratory. PARTICIPANTS: Twenty-five normal subjects separated into 2 groups: young (aged 20-39 years) and middle-aged (aged 40-60 years). INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Waking EEGs were recorded every 2 hours and subjective measures of alertness every 30 minutes during the 25-hour sleep-deprivation episode. Overall, results indicated no age-related differences over a 25-hour constant routine in the temporal evolution of subjective alertness and of spectral power in the theta/alpha (4-12 Hz) frequencies of the waking EEG. The middle-aged compared to the young subjects showed a reduced rebound of slow-wave activity in the recovery-sleep episode. While the waking EEG and subjective alertness levels showed strong correlations in both groups, there was no relationship between theta rise during wakefulness and slow-wave activity rebound in the recovery-sleep episode. CONCLUSIONS: These results suggest a dissociation in the middle-aged population between the sensitivity of their alertness level on the one hand and the sensitivity of their sleep on the other to the number of hours of wakefulness. Hence, alertness of young and middle-aged subjects would show the same deterioration with an accumulation of wakefulness (possibly reflecting a similar sleep need), yet the middle-aged subjects would be less able to increase their recuperative sleep intensity following enhanced time awake (reduction in sleep ability).