How Smart Is It to Go to Bed with the Phone? The Impact of Short-Wavelength Light and Affective States on Sleep and Circadian Rhythms

Abstract

Previously, we presented our preliminary results (N = 14) investigating the effects of short-wavelength light from a smartphone during the evening on sleep and circadian rhythms (Höhn et al., 2021). Here, we now demonstrate our full sample (N = 33 men), where polysomnography and body temperature were recorded during three experimental nights and subjects read for 90 min on a smartphone with or without a filter or from a book. Cortisol, melatonin and affectivity were assessed before and after sleep. These results confirm our earlier findings, indicating reduced slow-wave-sleep and -activity in the first night quarter after reading on the smartphone without a filter. The same was true for the cortisol-awakening-response. Although subjective sleepiness was not affected, the evening melatonin increase was attenuated in both smartphone conditions. Accordingly, the distal-proximal skin temperature gradient increased less after short-wavelength light exposure than after reading a book. Interestingly, we could unravel within this full dataset that higher positive affectivity in the evening predicted better subjective but not objective sleep quality. Our results show disruptive consequences of short-wavelength light for sleep and circadian rhythmicity with a partially attenuating effect of blue-light filters. Furthermore, affective states influence subjective sleep quality and should be considered, whenever investigating sleep and circadian rhythms.

Spectral slope and Lempel-Ziv complexity as robust markers of brain states during sleep and wakefulness

“…We utilized the data from a previously reported study (Höhn et al, 2021; Schmid et al, 2021) that investigated the effects of different light conditions on alertness, sleep and memory consolidation. The subjects underwent the same experimental protocol on three different days under highly controlled and standardized lighting conditions.…”

“…We utilized the data from a previously reported study (Höhn et al, 2021;Schmid et al, 2021) that investigated the effects of different light conditions on alertness, sleep and memory consolidation.…”

“…Before the first cued recall, another resting and Go/Nogo session were conducted. Afterwards, the participants had a 1.5 hours break from the tasks, in which they read stories under different light conditions (for details cf., Schmid et al, 2021). Before going to bed at approximately 11:00 pm, participants completed the last resting and Go/Nogo session of the day.…”

“…Participants had to react within 500ms for the response to be considered valid, but responses were recorded until 1000ms post-stimulus with reaction times longer than 500ms being regarded as attentional lapses. From each session, the performance score was computed by dividing the percentage of correct trials by the median reaction time of all valid responses (≤ 500ms, no errors) in milliseconds (Figueiro et al, 2016;Höhn et al, 2021).…”

Aktuelle Entwicklungen in der Schlafforschung und Schlafmedizin – eine Einschätzung der AG „Pädiatrie“

“…Handy, Gamen, TV und anderer Bildschirmkonsum sind zu einem der Hauptthemen geworden, denen sich die pädiatrische Schlafmedizin und -psychologie zu stellen hat. Insomnien und die Disruption chronobiologischer Rhythmen sind ungewollte Nebenwirkungen der Digitalisierung [ 24 , 25 ]. Hinzu kommt, dass Dialogstrukturen in Familien und Peergruppen labilisiert, gestört oder gar nicht erst entwickelt werden, was sich natürlich auch auf die Häufigkeit von Ein- und Durchschlafstörungen auswirkt.…”