Dim light melatonin onset following simulated eastward travel is earlier in young males genotyped as PER3^5/5 than PER3^4/4

Figures & data

Figure 1. Raster plot of the simulated jetlag protocol.

Table 1. Participant characteristics measured prior to the trial.

	PER3^4/4 (n = 8)	PER3^5/5 (n = 8)	p-value
Age (y)	23.0 (22.5, 27.5)	24.5 (21.5, 27.0)	0.959
Ethnicity (C: A: MA)	3: 4: 1 (38: 50: 12)	6: 2: 0 (75: 25: 0)	0.999
Height (cm)	178.5 (173.3, 182.0)	179.8 (171.8, 183.8)	0.721
Weight (kg)	72.7 (68.0, 87.0)	77.2 (68.3, 88.8)	0.574
BMI (kg∙m^−2)	24.09 (21.56, 27.23)	24.49 (20.64, 27.40)	1.000
Body fat (%)	17.7 (14.5, 23.2)	19.9 (14.3, 23.8)	0.878
RMR (kcal∙d^−1)	1556 (1391, 1954)	1757 (1380, 1839)	0.574
RER	0.78 (0.74, 0.83)	0.74 (0.70, 0.79)	0.161
HÖ score	45 (37, 58)	48 (45, 59)	0.328
PSQI score	3.5 (2.0, 4.7)	3.5 (2.2, 4.0)	0.798
Training (days·week^−1)	1.5 (1.0, 2.0)	1.0 (1.0, 1.3)	0.870
Bedtime (hh:mm)	00:15 (23:39, 01:50)	23:26 (22:48, 23.43)*	0.065
Wake-up time (hh:mm)	08:35 (07:18, 08:58)	07:32 (06:41, 07:37)*	0.354
Time-in-bed (h)	7.19 (6.55, 8.24)	7.53 (7.53, 8.05)*	0.171
Total sleep time (h)	6.20 (6.08, 7.20)	7.13 (6.52, 7.34)*	0.435
Sleep onset latency (min)	7.38 (2.46, 9.51)	1.20 (0.38, 16.02)*	0.943
Sleep efficiency (%)	88.71 (85.60, 89.68)	92.08 (82.43, 96.64)*	0.435
WASO (min)	28.27 (25.47, 42.10)	28.65 (11.81, 33.93)*	0.524

Data are presented as median with interquartile range (IQR; Q1, Q3) or counts. * n = 5. A: African; BMI: body mass index; C: Caucasian: HÖ: Horne-Östberg; MA: mixed ancestry; PER3: period 3 gene; PSQI: Pittsburgh Sleep Quality Index; RER: respiratory exchange ratio; RMR: resting metabolic rate; WASO: wake after sleep onset. Significance was determined using Mann-Whitney U or Fisher’s Exact tests.

Table 2. Sleep characteristics of the PER3^4/4 and PER3^5/5 groups during the first (SO1) and second (SO2) sleep opportunities.

	SO1		SO2		p-values
	PER3^4/4	PER3^5/5	PER3^4/4	PER3^5/5	p1	p2	p3	p4
TST (h)	7.22 (6.44, 7.39)	7.41 (7.33, 7.49)	6.80 (5.98, 7.22)	7.18 (6.90, 7.34)	0.026	0.203	0.109	0.008
SOL (min)	2.00 (1.00, 6.75)	1.75 (1.31, 2.81)	7.00 (5.31, 8.81)	2.63 (1.13, 6.38)	0.823	0.046	0.195	0.344
SE (%)	92.01 (84.32, 95.61)	95.96 (94.55, 97.86)	87.65 (76.64, 92.04)	91.33 (87.59, 94.65)	0.026	0.235	0.109	0.008
WASO (min)	22.50 (15.50, 39.94)	17.13 (9.44, 21.25)	26.38 (23.13, 49.31)	25.83 (21.19, 33.81)	0.223	0.666	0.313	0.023

Data are presented as median with IQR. PER3: period 3 gene, SE: sleep efficiency, SO: sleep opportunity, SOL: sleep onset latency, TST: total sleep time, WASO: wake after sleep onset. Significance was determined using Mann-Whitney U and Wilcoxon matched pairs tests. p₁: SO1 PER3^4/4 v PER3^5/5; p₂: SO2 PER3^4/4 v PER3^5/5; p₃: SO1 PER3^4/4 v SO2 PER3^4/4 and p₄: SO1 PER3^5/5 v SO2 PER3^5/5.

Figure 2. Changes in perceived sleepiness levels during constant routine (CR) 1, first day in new time zone (TZ) and CR2, as measured by the Stanford Sleepiness Scale in the PER3^4/4 and PER3^5/5 groups. Data are presented as median with interquartile ranges. Significance was determined using mixed effects linear regression models.

Figure 3. Changes in hourly salivary melatonin concentration and dim light melatonin onset (DLMO) during constant routines (CR) 1 and 2, respectively. A and B: All participants, C: PER3^4/4 group and D: PER3^5/5 group. Data are presented as median with interquartile ranges (A) or individual data points (B-D). The dotted lines indicates DLMO time for CR1 and CR2 at the DLMO threshold value of 4 pg⋅ml⁻¹. Significance was determined using Wilcoxon matched pairs test.

Figure 4. Changes in resting metabolic rate (A) and respiratory exchange ratio (B) measured before the trial and at 08h00 on days 1 and 2 in the new time zone. TZ D1 and D2: time zones days 1 and 2 respectively. Data are presented as median with 95% confidence intervals. Significance was determined using mixed effects linear regression models.