The periodicity of sleep duration – an infradian rhythm in spontaneous living

Figures & data

Figure 1 Habitual sleep duration (including, if any, daytime naps) for each participant across 14 consecutive days.

Note: X represents weekdays and O represents weekends.
Abbreviations: min, minutes; TST, total sleep time.

Table 1 Model parameters for each participant over a fortnight

Subject	Amplitude (minutes)	Frequency (day^−1)	Mesor (minutes)	Period (day)	RMS error (%)	P-value for amplitude
A	63	0.057	460	17.7	9.3	0.006a
B	90	0.439	427	2.3	29.8	0.018a
C	80	0.357	443	2.8	16.3	0.061
D	40	0.291	331	3.4	10.7	0.029a
E	54	0.271	395	3.7	10.7	0.007a
F	47	0.145	362	6.9	13.1	0.048a
G	104	0.160	379	6.2	28.9	0.013a
H	58	0.213	347	4.7	12.4	0.007a
I	79	0.180	317	5.6	23.5	0.025a
J	59	0.381	286	2.6	18.7	0.014a
K	64	0.209	361	4.8	15.6	0.033a
L	44	0.180	433	5.6	8.7	0.026a
M	68	0.309	487	3.2	11.9	0.036a

Note:

a Significant amplitude as obtained from the cosinor analysis.

Abbreviation: RMS, root mean square.