Spindle whorls were used to weight spindles when hand-spinning yarn. They were made in a variety of materials including stone, ceramic fragments and fired clay.

When were spindle whorls invented?

Date. Stoneware spindle whorls were common in the first half of the 16th century (Gaimster 1997, 248-250; fig. 104), possibly within a wider date range (Hurst and Moorhouse 1981).

Which stage of sleep lasts the longest?

In normal adults, REM sleep increases as the night progresses and is longest in the last one-third of the sleep episode. As the sleep episode progresses, stage 2 begins to account for the majority of NREM sleep, and stages 3 and 4 may sometimes altogether disappear.

What do sleep spindles indicate?

Sleep spindles are characteristic electroencephalogram (EEG) signatures of stage 2 non-rapid eye movement sleep. Implicated in sleep regulation and cognitive functioning, spindles may represent heritable biomarkers of neuropsychiatric disease.

At what age do sleep spindles appear?

Classical sleep spindles do not occur in prematures. They first appear clearly in the EEG during slow wave sleep from the 4th week postterm (44 weeks conceptional age) and are normally present in all infants EEGs by 9 weeks postterm.

Is 5 hours of deep sleep good?

Scientists agree that sleep is essential to health, and while stages 1 to 4 and REM sleep are all important, deep sleep is the most essential of all for feeling rested and staying healthy. The average healthy adult gets roughly 1 to 2 hours of deep sleep per 8 hours of nightly sleep.