Sleep is a critical part of our daily routine. We spend about a third of our time doing it and it’s as essential as food and water. Getting sufficient quality and quantity of sleep impacts our day-to-day performance, as well as our long-term health.
The amount of sleep we need and get reduces with age, from most of a newborn’s day spent with eyes closed, through around 10 hours in preschool and school age, to 7-9 hours for most adults (see figure 1). Older adults tend to need less sleep at around 7-8 hours. However, many adults are not getting their optimal amount and quality of sleep. Between our non-stop world, increasing demands on our time and increased stress and anxiety, it’s no surprise that 50-70million Americans are reported to have sleep or wakefulness disorders (NIH, 2023). It’s even been reported that “undiagnosed sleep apnea alone is estimated to cost the [US] Nation $150 billion annually”. Athletic populations may have a higher level of sleep disturbances due to travel, late night competitions and training commitments.
Sleep impacts our daily functioning, including reaction time, memory, mood, and physical performance. It is also known to be strongly associated with long term health, with less than 7 hours and more than 9 hours in middle-age being correlated with dementia risk from 70 years of age (Sabia et al, 2023). The same level of under-or over-sleeping has also been reported to potentially increase the risk of metabolic syndrome in young adults aged 18-24 years old (Nutrients | Free Full-Text | The Relationship between Sleep Duration and Metabolic Syndrome Severity Scores in Emerging Adults (mdpi.com)). This may be through the known impact of sleep on metabolic systems, including blood pressure, glucose homeostasis, and hormone regulation.
Tryptophan’s Influence on Sleep
As an essential amino acid, tryptophan is required in the diet since the human body cannot make it. Tryptophan, one of the amino acids in the diet that can cross the blood-brain barrier, is a precursor to serotonin, a neurotransmitter in the body that influences the sleep-wake cycle, mood, cognitive function and much more. This neurotransmitter is then converted into the hormone, melatonin (see figure 2). The uptake of tryptophan into the brain is also influenced by the level of other amino acids in the diet.
Some foods are richer in tryptophan, as highlighted below. Amongst some of the highest dietary sources is the whey protein fraction, alpha-lactalbumin.
Alpha-lactalbumin for enhanced sleep and overnight recovery
Alpha-lactalbumin and tryptophan have been tested for various measures of overnight recovery, sleep quality and quantity, morning wakefulness and cognitive performance. Essentially, it’s been tested to see if it improves sleep and favorably impacts performance the following day.
Some early work from Hartmann et al (1979) tested 250mg, 500mg or 1g tryptophan supplementation 20minutes before bedtime in those with longer sleep latencies (the time taken to fall asleep) of more than 30minutes. They found that supplementation with 250mg of tryptophan tended to reduce sleep latency and significantly increased the minutes in slow wave sleep.
Markus et al (2005) found that evening alpha-lactalbumin intake caused a 130% increase in Trp:LNAA before bedtime, and “modestly but significantly reduced sleepiness and improved brain-sustained attention processes the following morning”. Furthermore, in poor sleepers, this was accompanied by improved behavioral performance.
More recent work looked at whether supplementing semi-professional female rugby union players 2 hours before bed with for the duration of the season impacted any measures of sleep, including total sleep time, sleep efficiency, sleep onset latency and wake after sleep onset (Gratwicke et al, 2023). Alpha was found to reduce sleep onset latency compared to placebo, in particular during bye weeks (weeks with no competition) and during weeks of away games.
While MacInnes et al did not see an effect of acute alpha-lactalbumin intake in elite or serious recreational cyclist on either sleep quality or performance, this may have been due to the short intervention period.
Alpha-lactalbumin – more than just a source of tryptophan
Alpha-lac is the second most abundant fraction in whey protein and, as we know, whey protein has an unrivalled essential and branched-chain amino acid composition, being one of the highest sources of leucine available. While alpha does provide additional leucine compared to a standard whey, this invaluable array of amino acids gives something extra special – high quality protein the muscles and body thrive on.
While casein or milk protein is most commonly used in overnight recovery products, whey protein was recently shown to be as effective as caseinate for muscle protein synthesis when taken prior to bedtime (Trommelen et al, 2023).
Milk Specialties relentless quest for optimal ingredient solutions led to the addition of alpha-lactalbumin to our portfolio. With a number of product offerings available for multiple applications, please contact us to learn more about how to utilize our ingredient expertise for your products.
Chaudhry et al. Nutrients. 2023;15(4):1046
Gratwicke et al. Biol Sport. 2023;40(2):449-455
Hartmann and Spinweber. J Nerv Mental Dis. 1979; 167(8)
MacInnis et al. Int J Sport Nutr Exerc Metab. 2020;30(3):197-202