UNASSIGNED: Identifying intervention methods that target sleep characteristics involved in memory processing is a priority for the field of cognitive aging. Older adults with greater sleep efficiency and non-rapid eye movement slow-wave activity (SWA) (0.5-4 Hz electroencephalographic activity) tend to exhibit better memory and cognitive abilities. Paradoxically, long total sleep times are consistently associated with poorer cognition in older adults. Thus, maximizing sleep efficiency and SWA may be a priority relative to increasing mere total sleep time. As clinical behavioral sleep treatments do not consistently enhance SWA, and propensity for SWA increases with time spent awake, we examined with a proof-of concept pilot intervention whether a greater dose of time-in-bed (TiB) restriction (75% of habitual TiB) would increase both sleep efficiency and SWA in older adults with difficulties staying asleep without impairing memory performance.
UNASSIGNED: Participants were adults ages 55-80 with diary-reported sleep efficiency <90% and wake after sleep onset (WASO) >20 min. Sleep diary, actigraphy, polysomnography (PSG), and paired associate memory acquisition and retention were assessed before and after a week-long TiB restriction intervention (n = 30). TiB was restricted to 75% of diary-reported habitual TiB. A comparison group of n = 5 participants repeated assessments while following their usual sleep schedule to obtain preliminary estimates of effect sizes associated with repeated testing.
UNASSIGNED: Subjective and objective sleep measures robustly improved in the TiB restriction group for sleep quality, sleep depth, sleep efficiency and WASO, at the expense of TiB and time spent in N1 and N2 sleep. As hypothesized, SWA increased robustly with TiB restriction across the 0.5-4 Hz range, as well as subjective sleep depth, subjective and objective WASO. Despite increases in sleepiness ratings, no impairments were found in memory acquisition or retention.
UNASSIGNED: A TiB restriction dose equivalent to 75% of habitual TiB robustly increased sleep continuity and SWA in older adults with sleep maintenance difficulties, without impairing memory performance. These findings may inform long-term behavioral SWA enhancement interventions aimed at improving memory performance and risk for cognitive impairments.

UNASSIGNED: Sleep, in particular slow-wave sleep, is beneficial for memory consolidation. In two recent studies, a hypnotic suggestion to sleep more deeply increased the amount of slow-wave sleep in both a nap and a night design. In spite of these increases in slow-wave sleep, no beneficial effect on declarative memory consolidation was found. As coupling of slow-waves and sleep spindles is assumed to be critical for declarative memory consolidation during sleep, we hypothesized that the missing memory benefit after increased SWS could be related to a decrease in slow-wave/spindle coupling.
UNASSIGNED: Data from 33 highly hypnotizable subjects were retrieved from a nap (n = 14) and a night (n = 19) study with a similar design and procedure. After an adaptation session, subjects slept in the sleep laboratory for two experimental sessions with polysomnography. Prior to sleep, a paired-associate learning task was conducted. Next, subjects either listened to a hypnotic suggestion to sleep more deeply or to a control text in a randomized order according to a within-subject design. After sleep, subjects performed the recall of the memory task. Here, we conducted a fine-grained analysis of the sleep data on slow-waves, spindles and their coupling.
UNASSIGNED: In line with our hypothesis, listening to a hypnosis tape decreased the percentage of spindles coupled to slow-waves. Slow-wave parameters were consistently increased, but sleep spindles remained unaffected by the hypnotic suggestion.
UNASSIGNED: Our results suggest that selectively enhancing slow-waves without affecting sleep spindles might not be sufficient to improve memory consolidation during sleep.

High-frequency electroencephalographic activity (> 16 Hz activity) is often elevated during nonrapid eye movement sleep among individuals with insomnia, in line with the hyperarousal theory of insomnia. Evidence regarding sleep depth marked by slow-wave activity (< 4 Hz) is more mixed. Distinguishing subcomponents of slow-wave activity (slow-oscillation [< 1 Hz] or delta activity [1-4 Hz)]) may be critical in understanding these discrepancies, given that these oscillations have different neural generators and are functionally distinct. Here we tested the effects of insomnia diagnosis and insomnia treatment on nonrapid eye movement electroencephalography in older adults, distinguishing slow-oscillation and delta power.
In 93 older adults with insomnia and 71 good sleeper control participants (mean ages 68 years), effects of insomnia and cognitive behavioral therapy for insomnia (insomnia group only) on electroencephalographic spectral power were analyzed. Main effects and interactions with nonrapid eye movement period were assessed for the following frequency bands: slow-oscillation (0.5-1 Hz), delta (1-4 Hz), theta (4-8 Hz), alpha (8-12 Hz), sigma (12-16 Hz), and beta (16-32 Hz).
Slow-oscillation absolute and relative power were lower in the insomnia group compared with controls. There were no group differences in delta power. Insomnia was also associated with elevated 4-32 Hz absolute and relative power. After cognitive behavioral therapy for insomnia, absolute sigma and beta activity decreased.
Deficits in slow-wave activity in insomnia are specific to the slow-oscillation. Elevated high frequency activity is reduced for sigma and beta power following cognitive behavioral therapy for insomnia . These findings inform the pathophysiology of insomnia, including the mechanisms underlying cognitive behavioral therapy for insomnia in older adults.