Methods and compositions for biomarkers of fatigue

A method of guiding a human subject's sleep schedule, comprising:

• a) measuring the concentration of a peptide selected from the group consisting of:
• 1) a peptide comprising the amino acid sequence PPGKPQGPPPQGGNQPQGPPPPPGKPQ (SEQ ID NO:1), 2) a peptide comprising the amino acid sequence GNPQGPSPQGGNKPQGPPPPPGKPQ (SEQ ID NO:2), 3) a peptide comprising the amino acid sequence SPPGKPQGPPQQEGNKPQGPPPPGKPQ (SEQ ID NO:3), and 4) any combination thereof, in a saliva sample taken from the subject;
• b) calculating the ratio of the concentration of the peptide(s) measured in (a) to the total amount of protein in the sample, according to the equation:
• ([PPGKPQGPPPQGGNQPQGPPPPPGKPQ SEQ ID NO:1]+[GNPQGPSPQGGNKPQGPPPPPGKPQ SEQ ID NO:
• 2]+[SPPGKPQGPPQQEGNKPQGPPPPGKPQ SEQ ID NO;3])/total protein (μg);
• c) having the subject initiate or resume a sleep schedule;
• d) measuring the concentration of a peptide selected from the group consisting of:
• 1) a peptide comprising the amino acid sequence PPGKPQGPPPQGGNQPQGPPPPPGKPQ (SEQ ID NO:1), 2) a peptide comprising the amino acid sequence GNPQGPSPQGGNKPQGPPPPPGKPQ (SEQ ID NO:2), 3) a peptide comprising the amino acid sequence SPPGKPQGPPQQEGNKPQGPPPPGKPQ (SEQ ID NO:3), and 4) any combination thereof, in a saliva sample taken from the subject at one or more time points after (c), wherein the peptides of (d) are the same as the peptides of (a);
• e) calculating the ratio of the concentration of the peptide(s) measured in (d) to the total amount of protein in the sample, according to the equation:
• ([PPGKPQGPPPQGGNQPQGPPPPPGKPQ SEQ ID NO:1]+[GNPQGPSPQGGNKPQGPPPPPGKPQ SEQ ID NO:
• 2]+[SPPGKPQGPPQQEGNKPQGPPPPGKPQ SEQ ID NO;3])/total protein (μg);
• and
• f) guiding the subject's sleep schedule by modifying the duration of subsequent sleep periods using the subject's ratio(s) as calculated in (e), such that an increase in the ratio relative to the previous ratio leads to a subsequent increase in the duration of the subject's sleep period, and a decrease in the ratio or a constant ratio relative to the previous ratio leads to no change in the duration of the subject's sleep period or a subsequent decrease in the duration of the subject's sleep period.